meta-agl-bsp/recipes-kernel/linux/linux-yocto/4.8-0001-SEC-Backport-Fix-CVE-2017-1000364-through-backport.patch

   1 From 75349cc7326dd2aa645bf21fe65a40c68b386c29 Mon Sep 17 00:00:00 2001
   2 From: =?UTF-8?q?Jan-Simon=20M=C3=B6ller?= <jsmoeller@linuxfoundation.org>
   3 Date: Wed, 28 Jun 2017 00:35:18 +0200
   4 Subject: [PATCH] [SEC][Backport] Fix CVE-2017-1000364 through backport
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 Fix CVE-2017-1000364 through backport of upstream patches (from 4.9 branch):
  10 - https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/?h=linux-4.9.y&id=cfc0eb403816c5c4f9667d959de5e22789b5421e
  11 - https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/?h=linux-4.9.y&id=5d10ad6297260e9b85e7645ee544a6115bb229e4
  12 - https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/?h=linux-4.9.y&id=ce7fe8595902c3f03ef528c2dc1928b3f4b67fcf
  13
  14 Signed-off-by: Jan-Simon Möller <jsmoeller@linuxfoundation.org>
  15 ---
  16  Documentation/kernel-parameters.txt |   7 ++
  17  arch/arc/mm/mmap.c                  |   2 +-
  18  arch/arm/mm/mmap.c                  |   4 +-
  19  arch/frv/mm/elf-fdpic.c             |   2 +-
  20  arch/mips/mm/mmap.c                 |   2 +-
  21  arch/parisc/kernel/sys_parisc.c     |  15 ++--
  22  arch/powerpc/mm/hugetlbpage-radix.c |   2 +-
  23  arch/powerpc/mm/mmap.c              |   4 +-
  24  arch/powerpc/mm/slice.c             |   2 +-
  25  arch/s390/mm/mmap.c                 |   4 +-
  26  arch/sh/mm/mmap.c                   |   4 +-
  27  arch/sparc/kernel/sys_sparc_64.c    |   4 +-
  28  arch/sparc/mm/hugetlbpage.c         |   2 +-
  29  arch/tile/mm/hugetlbpage.c          |   2 +-
  30  arch/x86/kernel/sys_x86_64.c        |   4 +-
  31  arch/x86/mm/hugetlbpage.c           |   2 +-
  32  arch/xtensa/kernel/syscall.c        |   2 +-
  33  fs/hugetlbfs/inode.c                |   2 +-
  34  fs/proc/task_mmu.c                  |   4 -
  35  include/linux/mm.h                  |  53 ++++++------
  36  mm/gup.c                            |   5 --
  37  mm/memory.c                         |  38 ---------
  38  mm/mmap.c                           | 158 ++++++++++++++++++++++--------------
  39  23 files changed, 159 insertions(+), 165 deletions(-)
  40
  41 diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
  42 index 46726d4899fe..c1980b5c6a15 100644
  43 --- a/Documentation/kernel-parameters.txt
  44 +++ b/Documentation/kernel-parameters.txt
  45 @@ -3852,6 +3852,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
  46         spia_pedr=
  47         spia_peddr=
  48
  49 +       stack_guard_gap=        [MM]
  50 +                       override the default stack gap protection. The value
  51 +                       is in page units and it defines how many pages prior
  52 +                       to (for stacks growing down) resp. after (for stacks
  53 +                       growing up) the main stack are reserved for no other
  54 +                       mapping. Default value is 256 pages.
  55 +
  56         stacktrace      [FTRACE]
  57                         Enabled the stack tracer on boot up.
  58
  59 diff --git a/arch/arc/mm/mmap.c b/arch/arc/mm/mmap.c
  60 index 2e06d56e987b..cf4ae6958240 100644
  61 --- a/arch/arc/mm/mmap.c
  62 +++ b/arch/arc/mm/mmap.c
  63 @@ -64,7 +64,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
  64
  65                 vma = find_vma(mm, addr);
  66                 if (TASK_SIZE - len >= addr &&
  67 -                   (!vma || addr + len <= vma->vm_start))
  68 +                   (!vma || addr + len <= vm_start_gap(vma)))
  69                         return addr;
  70         }
  71
  72 diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
  73 index 66353caa35b9..641334ebf46d 100644
  74 --- a/arch/arm/mm/mmap.c
  75 +++ b/arch/arm/mm/mmap.c
  76 @@ -89,7 +89,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
  77
  78                 vma = find_vma(mm, addr);
  79                 if (TASK_SIZE - len >= addr &&
  80 -                   (!vma || addr + len <= vma->vm_start))
  81 +                   (!vma || addr + len <= vm_start_gap(vma)))
  82                         return addr;
  83         }
  84
  85 @@ -140,7 +140,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
  86                         addr = PAGE_ALIGN(addr);
  87                 vma = find_vma(mm, addr);
  88                 if (TASK_SIZE - len >= addr &&
  89 -                               (!vma || addr + len <= vma->vm_start))
  90 +                               (!vma || addr + len <= vm_start_gap(vma)))
  91                         return addr;
  92         }
  93
  94 diff --git a/arch/frv/mm/elf-fdpic.c b/arch/frv/mm/elf-fdpic.c
  95 index 836f14707a62..efa59f1f8022 100644
  96 --- a/arch/frv/mm/elf-fdpic.c
  97 +++ b/arch/frv/mm/elf-fdpic.c
  98 @@ -74,7 +74,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
  99                 addr = PAGE_ALIGN(addr);
 100                 vma = find_vma(current->mm, addr);
 101                 if (TASK_SIZE - len >= addr &&
 102 -                   (!vma || addr + len <= vma->vm_start))
 103 +                   (!vma || addr + len <= vm_start_gap(vma)))
 104                         goto success;
 105         }
 106
 107 diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c
 108 index 353037699512..c5fdea5debe5 100644
 109 --- a/arch/mips/mm/mmap.c
 110 +++ b/arch/mips/mm/mmap.c
 111 @@ -92,7 +92,7 @@ static unsigned long arch_get_unmapped_area_common(struct file *filp,
 112
 113                 vma = find_vma(mm, addr);
 114                 if (TASK_SIZE - len >= addr &&
 115 -                   (!vma || addr + len <= vma->vm_start))
 116 +                   (!vma || addr + len <= vm_start_gap(vma)))
 117                         return addr;
 118         }
 119
 120 diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
 121 index 0a393a04e891..1d7691fa8ab2 100644
 122 --- a/arch/parisc/kernel/sys_parisc.c
 123 +++ b/arch/parisc/kernel/sys_parisc.c
 124 @@ -88,7 +88,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 125                 unsigned long len, unsigned long pgoff, unsigned long flags)
 126  {
 127         struct mm_struct *mm = current->mm;
 128 -       struct vm_area_struct *vma;
 129 +       struct vm_area_struct *vma, *prev;
 130         unsigned long task_size = TASK_SIZE;
 131         int do_color_align, last_mmap;
 132         struct vm_unmapped_area_info info;
 133 @@ -115,9 +115,10 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 134                 else
 135                         addr = PAGE_ALIGN(addr);
 136
 137 -               vma = find_vma(mm, addr);
 138 +               vma = find_vma_prev(mm, addr, &prev);
 139                 if (task_size - len >= addr &&
 140 -                   (!vma || addr + len <= vma->vm_start))
 141 +                   (!vma || addr + len <= vm_start_gap(vma)) &&
 142 +                   (!prev || addr >= vm_end_gap(prev)))
 143                         goto found_addr;
 144         }
 145
 146 @@ -141,7 +142,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 147                           const unsigned long len, const unsigned long pgoff,
 148                           const unsigned long flags)
 149  {
 150 -       struct vm_area_struct *vma;
 151 +       struct vm_area_struct *vma, *prev;
 152         struct mm_struct *mm = current->mm;
 153         unsigned long addr = addr0;
 154         int do_color_align, last_mmap;
 155 @@ -175,9 +176,11 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 156                         addr = COLOR_ALIGN(addr, last_mmap, pgoff);
 157                 else
 158                         addr = PAGE_ALIGN(addr);
 159 -               vma = find_vma(mm, addr);
 160 +
 161 +               vma = find_vma_prev(mm, addr, &prev);
 162                 if (TASK_SIZE - len >= addr &&
 163 -                   (!vma || addr + len <= vma->vm_start))
 164 +                   (!vma || addr + len <= vm_start_gap(vma)) &&
 165 +                   (!prev || addr >= vm_end_gap(prev)))
 166                         goto found_addr;
 167         }
 168
 169 diff --git a/arch/powerpc/mm/hugetlbpage-radix.c b/arch/powerpc/mm/hugetlbpage-radix.c
 170 index 35254a678456..a2b2d97f7eda 100644
 171 --- a/arch/powerpc/mm/hugetlbpage-radix.c
 172 +++ b/arch/powerpc/mm/hugetlbpage-radix.c
 173 @@ -65,7 +65,7 @@ radix__hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 174                 addr = ALIGN(addr, huge_page_size(h));
 175                 vma = find_vma(mm, addr);
 176                 if (TASK_SIZE - len >= addr &&
 177 -                   (!vma || addr + len <= vma->vm_start))
 178 +                   (!vma || addr + len <= vm_start_gap(vma)))
 179                         return addr;
 180         }
 181         /*
 182 diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c
 183 index 2f1e44362198..5bc2845cddf4 100644
 184 --- a/arch/powerpc/mm/mmap.c
 185 +++ b/arch/powerpc/mm/mmap.c
 186 @@ -106,7 +106,7 @@ radix__arch_get_unmapped_area(struct file *filp, unsigned long addr,
 187                 addr = PAGE_ALIGN(addr);
 188                 vma = find_vma(mm, addr);
 189                 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
 190 -                   (!vma || addr + len <= vma->vm_start))
 191 +                   (!vma || addr + len <= vm_start_gap(vma)))
 192                         return addr;
 193         }
 194
 195 @@ -142,7 +142,7 @@ radix__arch_get_unmapped_area_topdown(struct file *filp,
 196                 addr = PAGE_ALIGN(addr);
 197                 vma = find_vma(mm, addr);
 198                 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
 199 -                               (!vma || addr + len <= vma->vm_start))
 200 +                               (!vma || addr + len <= vm_start_gap(vma)))
 201                         return addr;
 202         }
 203
 204 diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
 205 index 2b27458902ee..c4d5c9c61e0f 100644
 206 --- a/arch/powerpc/mm/slice.c
 207 +++ b/arch/powerpc/mm/slice.c
 208 @@ -105,7 +105,7 @@ static int slice_area_is_free(struct mm_struct *mm, unsigned long addr,
 209         if ((mm->task_size - len) < addr)
 210                 return 0;
 211         vma = find_vma(mm, addr);
 212 -       return (!vma || (addr + len) <= vma->vm_start);
 213 +       return (!vma || (addr + len) <= vm_start_gap(vma));
 214  }
 215
 216  static int slice_low_has_vma(struct mm_struct *mm, unsigned long slice)
 217 diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
 218 index eb9df2822da1..812368f274c9 100644
 219 --- a/arch/s390/mm/mmap.c
 220 +++ b/arch/s390/mm/mmap.c
 221 @@ -98,7 +98,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 222                 addr = PAGE_ALIGN(addr);
 223                 vma = find_vma(mm, addr);
 224                 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
 225 -                   (!vma || addr + len <= vma->vm_start))
 226 +                   (!vma || addr + len <= vm_start_gap(vma)))
 227                         return addr;
 228         }
 229
 230 @@ -136,7 +136,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 231                 addr = PAGE_ALIGN(addr);
 232                 vma = find_vma(mm, addr);
 233                 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
 234 -                               (!vma || addr + len <= vma->vm_start))
 235 +                               (!vma || addr + len <= vm_start_gap(vma)))
 236                         return addr;
 237         }
 238
 239 diff --git a/arch/sh/mm/mmap.c b/arch/sh/mm/mmap.c
 240 index 6777177807c2..7df7d5944188 100644
 241 --- a/arch/sh/mm/mmap.c
 242 +++ b/arch/sh/mm/mmap.c
 243 @@ -63,7 +63,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 244
 245                 vma = find_vma(mm, addr);
 246                 if (TASK_SIZE - len >= addr &&
 247 -                   (!vma || addr + len <= vma->vm_start))
 248 +                   (!vma || addr + len <= vm_start_gap(vma)))
 249                         return addr;
 250         }
 251
 252 @@ -113,7 +113,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 253
 254                 vma = find_vma(mm, addr);
 255                 if (TASK_SIZE - len >= addr &&
 256 -                   (!vma || addr + len <= vma->vm_start))
 257 +                   (!vma || addr + len <= vm_start_gap(vma)))
 258                         return addr;
 259         }
 260
 261 diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
 262 index fe8b8ee8e660..02e05e221b94 100644
 263 --- a/arch/sparc/kernel/sys_sparc_64.c
 264 +++ b/arch/sparc/kernel/sys_sparc_64.c
 265 @@ -118,7 +118,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
 266
 267                 vma = find_vma(mm, addr);
 268                 if (task_size - len >= addr &&
 269 -                   (!vma || addr + len <= vma->vm_start))
 270 +                   (!vma || addr + len <= vm_start_gap(vma)))
 271                         return addr;
 272         }
 273
 274 @@ -181,7 +181,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 275
 276                 vma = find_vma(mm, addr);
 277                 if (task_size - len >= addr &&
 278 -                   (!vma || addr + len <= vma->vm_start))
 279 +                   (!vma || addr + len <= vm_start_gap(vma)))
 280                         return addr;
 281         }
 282
 283 diff --git a/arch/sparc/mm/hugetlbpage.c b/arch/sparc/mm/hugetlbpage.c
 284 index 988acc8b1b80..58cde8d9be8a 100644
 285 --- a/arch/sparc/mm/hugetlbpage.c
 286 +++ b/arch/sparc/mm/hugetlbpage.c
 287 @@ -116,7 +116,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 288                 addr = ALIGN(addr, HPAGE_SIZE);
 289                 vma = find_vma(mm, addr);
 290                 if (task_size - len >= addr &&
 291 -                   (!vma || addr + len <= vma->vm_start))
 292 +                   (!vma || addr + len <= vm_start_gap(vma)))
 293                         return addr;
 294         }
 295         if (mm->get_unmapped_area == arch_get_unmapped_area)
 296 diff --git a/arch/tile/mm/hugetlbpage.c b/arch/tile/mm/hugetlbpage.c
 297 index 77ceaa343fce..67508b249ede 100644
 298 --- a/arch/tile/mm/hugetlbpage.c
 299 +++ b/arch/tile/mm/hugetlbpage.c
 300 @@ -232,7 +232,7 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 301                 addr = ALIGN(addr, huge_page_size(h));
 302                 vma = find_vma(mm, addr);
 303                 if (TASK_SIZE - len >= addr &&
 304 -                   (!vma || addr + len <= vma->vm_start))
 305 +                   (!vma || addr + len <= vm_start_gap(vma)))
 306                         return addr;
 307         }
 308         if (current->mm->get_unmapped_area == arch_get_unmapped_area)
 309 diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
 310 index 10e0272d789a..136ad7c1ce7b 100644
 311 --- a/arch/x86/kernel/sys_x86_64.c
 312 +++ b/arch/x86/kernel/sys_x86_64.c
 313 @@ -143,7 +143,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 314                 addr = PAGE_ALIGN(addr);
 315                 vma = find_vma(mm, addr);
 316                 if (end - len >= addr &&
 317 -                   (!vma || addr + len <= vma->vm_start))
 318 +                   (!vma || addr + len <= vm_start_gap(vma)))
 319                         return addr;
 320         }
 321
 322 @@ -186,7 +186,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 323                 addr = PAGE_ALIGN(addr);
 324                 vma = find_vma(mm, addr);
 325                 if (TASK_SIZE - len >= addr &&
 326 -                               (!vma || addr + len <= vma->vm_start))
 327 +                               (!vma || addr + len <= vm_start_gap(vma)))
 328                         return addr;
 329         }
 330
 331 diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
 332 index 2ae8584b44c7..fe342e8ed529 100644
 333 --- a/arch/x86/mm/hugetlbpage.c
 334 +++ b/arch/x86/mm/hugetlbpage.c
 335 @@ -144,7 +144,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 336                 addr = ALIGN(addr, huge_page_size(h));
 337                 vma = find_vma(mm, addr);
 338                 if (TASK_SIZE - len >= addr &&
 339 -                   (!vma || addr + len <= vma->vm_start))
 340 +                   (!vma || addr + len <= vm_start_gap(vma)))
 341                         return addr;
 342         }
 343         if (mm->get_unmapped_area == arch_get_unmapped_area)
 344 diff --git a/arch/xtensa/kernel/syscall.c b/arch/xtensa/kernel/syscall.c
 345 index 83cf49685373..3aaaae18417c 100644
 346 --- a/arch/xtensa/kernel/syscall.c
 347 +++ b/arch/xtensa/kernel/syscall.c
 348 @@ -87,7 +87,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 349                 /* At this point:  (!vmm || addr < vmm->vm_end). */
 350                 if (TASK_SIZE - len < addr)
 351                         return -ENOMEM;
 352 -               if (!vmm || addr + len <= vmm->vm_start)
 353 +               if (!vmm || addr + len <= vm_start_gap(vmm))
 354                         return addr;
 355                 addr = vmm->vm_end;
 356                 if (flags & MAP_SHARED)
 357 diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
 358 index 4ea71eba40a5..aac9114728c3 100644
 359 --- a/fs/hugetlbfs/inode.c
 360 +++ b/fs/hugetlbfs/inode.c
 361 @@ -191,7 +191,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 362                 addr = ALIGN(addr, huge_page_size(h));
 363                 vma = find_vma(mm, addr);
 364                 if (TASK_SIZE - len >= addr &&
 365 -                   (!vma || addr + len <= vma->vm_start))
 366 +                   (!vma || addr + len <= vm_start_gap(vma)))
 367                         return addr;
 368         }
 369
 370 diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
 371 index 2750949397eb..5feada822930 100644
 372 --- a/fs/proc/task_mmu.c
 373 +++ b/fs/proc/task_mmu.c
 374 @@ -309,11 +309,7 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
 375
 376         /* We don't show the stack guard page in /proc/maps */
 377         start = vma->vm_start;
 378 -       if (stack_guard_page_start(vma, start))
 379 -               start += PAGE_SIZE;
 380         end = vma->vm_end;
 381 -       if (stack_guard_page_end(vma, end))
 382 -               end -= PAGE_SIZE;
 383
 384         seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
 385         seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
 386 diff --git a/include/linux/mm.h b/include/linux/mm.h
 387 index 582d30baaa86..31206cc2e99c 100644
 388 --- a/include/linux/mm.h
 389 +++ b/include/linux/mm.h
 390 @@ -1392,39 +1392,11 @@ int clear_page_dirty_for_io(struct page *page);
 391
 392  int get_cmdline(struct task_struct *task, char *buffer, int buflen);
 393
 394 -/* Is the vma a continuation of the stack vma above it? */
 395 -static inline int vma_growsdown(struct vm_area_struct *vma, unsigned long addr)
 396 -{
 397 -       return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN);
 398 -}
 399 -
 400  static inline bool vma_is_anonymous(struct vm_area_struct *vma)
 401  {
 402         return !vma->vm_ops;
 403  }
 404
 405 -static inline int stack_guard_page_start(struct vm_area_struct *vma,
 406 -                                            unsigned long addr)
 407 -{
 408 -       return (vma->vm_flags & VM_GROWSDOWN) &&
 409 -               (vma->vm_start == addr) &&
 410 -               !vma_growsdown(vma->vm_prev, addr);
 411 -}
 412 -
 413 -/* Is the vma a continuation of the stack vma below it? */
 414 -static inline int vma_growsup(struct vm_area_struct *vma, unsigned long addr)
 415 -{
 416 -       return vma && (vma->vm_start == addr) && (vma->vm_flags & VM_GROWSUP);
 417 -}
 418 -
 419 -static inline int stack_guard_page_end(struct vm_area_struct *vma,
 420 -                                          unsigned long addr)
 421 -{
 422 -       return (vma->vm_flags & VM_GROWSUP) &&
 423 -               (vma->vm_end == addr) &&
 424 -               !vma_growsup(vma->vm_next, addr);
 425 -}
 426 -
 427  int vma_is_stack_for_task(struct vm_area_struct *vma, struct task_struct *t);
 428
 429  extern unsigned long move_page_tables(struct vm_area_struct *vma,
 430 @@ -2153,6 +2125,7 @@ void page_cache_async_readahead(struct address_space *mapping,
 431                                 pgoff_t offset,
 432                                 unsigned long size);
 433
 434 +extern unsigned long stack_guard_gap;
 435  /* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */
 436  extern int expand_stack(struct vm_area_struct *vma, unsigned long address);
 437
 438 @@ -2181,6 +2154,30 @@ static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * m
 439         return vma;
 440  }
 441
 442 +static inline unsigned long vm_start_gap(struct vm_area_struct *vma)
 443 +{
 444 +       unsigned long vm_start = vma->vm_start;
 445 +
 446 +       if (vma->vm_flags & VM_GROWSDOWN) {
 447 +               vm_start -= stack_guard_gap;
 448 +               if (vm_start > vma->vm_start)
 449 +                       vm_start = 0;
 450 +       }
 451 +       return vm_start;
 452 +}
 453 +
 454 +static inline unsigned long vm_end_gap(struct vm_area_struct *vma)
 455 +{
 456 +       unsigned long vm_end = vma->vm_end;
 457 +
 458 +       if (vma->vm_flags & VM_GROWSUP) {
 459 +               vm_end += stack_guard_gap;
 460 +               if (vm_end < vma->vm_end)
 461 +                       vm_end = -PAGE_SIZE;
 462 +       }
 463 +       return vm_end;
 464 +}
 465 +
 466  static inline unsigned long vma_pages(struct vm_area_struct *vma)
 467  {
 468         return (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 469 diff --git a/mm/gup.c b/mm/gup.c
 470 index 22cc22e7432f..4b3723734623 100644
 471 --- a/mm/gup.c
 472 +++ b/mm/gup.c
 473 @@ -370,11 +370,6 @@ static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma,
 474         /* mlock all present pages, but do not fault in new pages */
 475         if ((*flags & (FOLL_POPULATE | FOLL_MLOCK)) == FOLL_MLOCK)
 476                 return -ENOENT;
 477 -       /* For mm_populate(), just skip the stack guard page. */
 478 -       if ((*flags & FOLL_POPULATE) &&
 479 -                       (stack_guard_page_start(vma, address) ||
 480 -                        stack_guard_page_end(vma, address + PAGE_SIZE)))
 481 -               return -ENOENT;
 482         if (*flags & FOLL_WRITE)
 483                 fault_flags |= FAULT_FLAG_WRITE;
 484         if (*flags & FOLL_REMOTE)
 485 diff --git a/mm/memory.c b/mm/memory.c
 486 index 45f39f391cc2..527ef7841146 100644
 487 --- a/mm/memory.c
 488 +++ b/mm/memory.c
 489 @@ -2695,40 +2695,6 @@ out_release:
 490  }
 491
 492  /*
 493 - * This is like a special single-page "expand_{down|up}wards()",
 494 - * except we must first make sure that 'address{-|+}PAGE_SIZE'
 495 - * doesn't hit another vma.
 496 - */
 497 -static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
 498 -{
 499 -       address &= PAGE_MASK;
 500 -       if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
 501 -               struct vm_area_struct *prev = vma->vm_prev;
 502 -
 503 -               /*
 504 -                * Is there a mapping abutting this one below?
 505 -                *
 506 -                * That's only ok if it's the same stack mapping
 507 -                * that has gotten split..
 508 -                */
 509 -               if (prev && prev->vm_end == address)
 510 -                       return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
 511 -
 512 -               return expand_downwards(vma, address - PAGE_SIZE);
 513 -       }
 514 -       if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
 515 -               struct vm_area_struct *next = vma->vm_next;
 516 -
 517 -               /* As VM_GROWSDOWN but s/below/above/ */
 518 -               if (next && next->vm_start == address + PAGE_SIZE)
 519 -                       return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
 520 -
 521 -               return expand_upwards(vma, address + PAGE_SIZE);
 522 -       }
 523 -       return 0;
 524 -}
 525 -
 526 -/*
 527   * We enter with non-exclusive mmap_sem (to exclude vma changes,
 528   * but allow concurrent faults), and pte mapped but not yet locked.
 529   * We return with mmap_sem still held, but pte unmapped and unlocked.
 530 @@ -2744,10 +2710,6 @@ static int do_anonymous_page(struct fault_env *fe)
 531         if (vma->vm_flags & VM_SHARED)
 532                 return VM_FAULT_SIGBUS;
 533
 534 -       /* Check if we need to add a guard page to the stack */
 535 -       if (check_stack_guard_page(vma, fe->address) < 0)
 536 -               return VM_FAULT_SIGSEGV;
 537 -
 538         /*
 539          * Use pte_alloc() instead of pte_alloc_map().  We can't run
 540          * pte_offset_map() on pmds where a huge pmd might be created
 541 diff --git a/mm/mmap.c b/mm/mmap.c
 542 index f3ebc5a54367..e1c1eb4b3942 100644
 543 --- a/mm/mmap.c
 544 +++ b/mm/mmap.c
 545 @@ -176,6 +176,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 546         unsigned long retval;
 547         unsigned long newbrk, oldbrk;
 548         struct mm_struct *mm = current->mm;
 549 +       struct vm_area_struct *next;
 550         unsigned long min_brk;
 551         bool populate;
 552
 553 @@ -221,7 +222,8 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 554         }
 555
 556         /* Check against existing mmap mappings. */
 557 -       if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
 558 +       next = find_vma(mm, oldbrk);
 559 +       if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
 560                 goto out;
 561
 562         /* Ok, looks good - let it rip. */
 563 @@ -244,10 +246,22 @@ out:
 564
 565  static long vma_compute_subtree_gap(struct vm_area_struct *vma)
 566  {
 567 -       unsigned long max, subtree_gap;
 568 -       max = vma->vm_start;
 569 -       if (vma->vm_prev)
 570 -               max -= vma->vm_prev->vm_end;
 571 +       unsigned long max, prev_end, subtree_gap;
 572 +
 573 +       /*
 574 +        * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we
 575 +        * allow two stack_guard_gaps between them here, and when choosing
 576 +        * an unmapped area; whereas when expanding we only require one.
 577 +        * That's a little inconsistent, but keeps the code here simpler.
 578 +        */
 579 +       max = vm_start_gap(vma);
 580 +       if (vma->vm_prev) {
 581 +               prev_end = vm_end_gap(vma->vm_prev);
 582 +               if (max > prev_end)
 583 +                       max -= prev_end;
 584 +               else
 585 +                       max = 0;
 586 +       }
 587         if (vma->vm_rb.rb_left) {
 588                 subtree_gap = rb_entry(vma->vm_rb.rb_left,
 589                                 struct vm_area_struct, vm_rb)->rb_subtree_gap;
 590 @@ -343,7 +357,7 @@ static void validate_mm(struct mm_struct *mm)
 591                         anon_vma_unlock_read(anon_vma);
 592                 }
 593
 594 -               highest_address = vma->vm_end;
 595 +               highest_address = vm_end_gap(vma);
 596                 vma = vma->vm_next;
 597                 i++;
 598         }
 599 @@ -512,7 +526,7 @@ void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
 600         if (vma->vm_next)
 601                 vma_gap_update(vma->vm_next);
 602         else
 603 -               mm->highest_vm_end = vma->vm_end;
 604 +               mm->highest_vm_end = vm_end_gap(vma);
 605
 606         /*
 607          * vma->vm_prev wasn't known when we followed the rbtree to find the
 608 @@ -765,7 +779,7 @@ again:
 609                         vma_gap_update(vma);
 610                 if (end_changed) {
 611                         if (!next)
 612 -                               mm->highest_vm_end = end;
 613 +                               mm->highest_vm_end = vm_end_gap(vma);
 614                         else if (!adjust_next)
 615                                 vma_gap_update(next);
 616                 }
 617 @@ -1630,7 +1644,7 @@ unsigned long unmapped_area(struct vm_unmapped_area_info *info)
 618
 619         while (true) {
 620                 /* Visit left subtree if it looks promising */
 621 -               gap_end = vma->vm_start;
 622 +               gap_end = vm_start_gap(vma);
 623                 if (gap_end >= low_limit && vma->vm_rb.rb_left) {
 624                         struct vm_area_struct *left =
 625                                 rb_entry(vma->vm_rb.rb_left,
 626 @@ -1641,12 +1655,13 @@ unsigned long unmapped_area(struct vm_unmapped_area_info *info)
 627                         }
 628                 }
 629
 630 -               gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
 631 +               gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
 632  check_current:
 633                 /* Check if current node has a suitable gap */
 634                 if (gap_start > high_limit)
 635                         return -ENOMEM;
 636 -               if (gap_end >= low_limit && gap_end - gap_start >= length)
 637 +               if (gap_end >= low_limit &&
 638 +                   gap_end > gap_start && gap_end - gap_start >= length)
 639                         goto found;
 640
 641                 /* Visit right subtree if it looks promising */
 642 @@ -1668,8 +1683,8 @@ check_current:
 643                         vma = rb_entry(rb_parent(prev),
 644                                        struct vm_area_struct, vm_rb);
 645                         if (prev == vma->vm_rb.rb_left) {
 646 -                               gap_start = vma->vm_prev->vm_end;
 647 -                               gap_end = vma->vm_start;
 648 +                               gap_start = vm_end_gap(vma->vm_prev);
 649 +                               gap_end = vm_start_gap(vma);
 650                                 goto check_current;
 651                         }
 652                 }
 653 @@ -1733,7 +1748,7 @@ unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
 654
 655         while (true) {
 656                 /* Visit right subtree if it looks promising */
 657 -               gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
 658 +               gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
 659                 if (gap_start <= high_limit && vma->vm_rb.rb_right) {
 660                         struct vm_area_struct *right =
 661                                 rb_entry(vma->vm_rb.rb_right,
 662 @@ -1746,10 +1761,11 @@ unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
 663
 664  check_current:
 665                 /* Check if current node has a suitable gap */
 666 -               gap_end = vma->vm_start;
 667 +               gap_end = vm_start_gap(vma);
 668                 if (gap_end < low_limit)
 669                         return -ENOMEM;
 670 -               if (gap_start <= high_limit && gap_end - gap_start >= length)
 671 +               if (gap_start <= high_limit &&
 672 +                   gap_end > gap_start && gap_end - gap_start >= length)
 673                         goto found;
 674
 675                 /* Visit left subtree if it looks promising */
 676 @@ -1772,7 +1788,7 @@ check_current:
 677                                        struct vm_area_struct, vm_rb);
 678                         if (prev == vma->vm_rb.rb_right) {
 679                                 gap_start = vma->vm_prev ?
 680 -                                       vma->vm_prev->vm_end : 0;
 681 +                                       vm_end_gap(vma->vm_prev) : 0;
 682                                 goto check_current;
 683                         }
 684                 }
 685 @@ -1810,7 +1826,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 686                 unsigned long len, unsigned long pgoff, unsigned long flags)
 687  {
 688         struct mm_struct *mm = current->mm;
 689 -       struct vm_area_struct *vma;
 690 +       struct vm_area_struct *vma, *prev;
 691         struct vm_unmapped_area_info info;
 692
 693         if (len > TASK_SIZE - mmap_min_addr)
 694 @@ -1821,9 +1837,10 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 695
 696         if (addr) {
 697                 addr = PAGE_ALIGN(addr);
 698 -               vma = find_vma(mm, addr);
 699 +               vma = find_vma_prev(mm, addr, &prev);
 700                 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
 701 -                   (!vma || addr + len <= vma->vm_start))
 702 +                   (!vma || addr + len <= vm_start_gap(vma)) &&
 703 +                   (!prev || addr >= vm_end_gap(prev)))
 704                         return addr;
 705         }
 706
 707 @@ -1846,7 +1863,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 708                           const unsigned long len, const unsigned long pgoff,
 709                           const unsigned long flags)
 710  {
 711 -       struct vm_area_struct *vma;
 712 +       struct vm_area_struct *vma, *prev;
 713         struct mm_struct *mm = current->mm;
 714         unsigned long addr = addr0;
 715         struct vm_unmapped_area_info info;
 716 @@ -1861,9 +1878,10 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 717         /* requesting a specific address */
 718         if (addr) {
 719                 addr = PAGE_ALIGN(addr);
 720 -               vma = find_vma(mm, addr);
 721 +               vma = find_vma_prev(mm, addr, &prev);
 722                 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
 723 -                               (!vma || addr + len <= vma->vm_start))
 724 +                               (!vma || addr + len <= vm_start_gap(vma)) &&
 725 +                               (!prev || addr >= vm_end_gap(prev)))
 726                         return addr;
 727         }
 728
 729 @@ -1998,21 +2016,19 @@ find_vma_prev(struct mm_struct *mm, unsigned long addr,
 730   * update accounting. This is shared with both the
 731   * grow-up and grow-down cases.
 732   */
 733 -static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
 734 +static int acct_stack_growth(struct vm_area_struct *vma,
 735 +                            unsigned long size, unsigned long grow)
 736  {
 737         struct mm_struct *mm = vma->vm_mm;
 738         struct rlimit *rlim = current->signal->rlim;
 739 -       unsigned long new_start, actual_size;
 740 +       unsigned long new_start;
 741
 742         /* address space limit tests */
 743         if (!may_expand_vm(mm, vma->vm_flags, grow))
 744                 return -ENOMEM;
 745
 746         /* Stack limit test */
 747 -       actual_size = size;
 748 -       if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN)))
 749 -               actual_size -= PAGE_SIZE;
 750 -       if (actual_size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
 751 +       if (size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
 752                 return -ENOMEM;
 753
 754         /* mlock limit tests */
 755 @@ -2050,16 +2066,32 @@ static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, uns
 756  int expand_upwards(struct vm_area_struct *vma, unsigned long address)
 757  {
 758         struct mm_struct *mm = vma->vm_mm;
 759 +       struct vm_area_struct *next;
 760 +       unsigned long gap_addr;
 761         int error = 0;
 762
 763         if (!(vma->vm_flags & VM_GROWSUP))
 764                 return -EFAULT;
 765
 766 -       /* Guard against wrapping around to address 0. */
 767 -       if (address < PAGE_ALIGN(address+4))
 768 -               address = PAGE_ALIGN(address+4);
 769 -       else
 770 +       /* Guard against exceeding limits of the address space. */
 771 +       address &= PAGE_MASK;
 772 +       if (address >= TASK_SIZE)
 773                 return -ENOMEM;
 774 +       address += PAGE_SIZE;
 775 +
 776 +       /* Enforce stack_guard_gap */
 777 +       gap_addr = address + stack_guard_gap;
 778 +
 779 +       /* Guard against overflow */
 780 +       if (gap_addr < address || gap_addr > TASK_SIZE)
 781 +               gap_addr = TASK_SIZE;
 782 +
 783 +       next = vma->vm_next;
 784 +       if (next && next->vm_start < gap_addr) {
 785 +               if (!(next->vm_flags & VM_GROWSUP))
 786 +                       return -ENOMEM;
 787 +               /* Check that both stack segments have the same anon_vma? */
 788 +       }
 789
 790         /* We must make sure the anon_vma is allocated. */
 791         if (unlikely(anon_vma_prepare(vma)))
 792 @@ -2104,7 +2136,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
 793                                 if (vma->vm_next)
 794                                         vma_gap_update(vma->vm_next);
 795                                 else
 796 -                                       mm->highest_vm_end = address;
 797 +                                       mm->highest_vm_end = vm_end_gap(vma);
 798                                 spin_unlock(&mm->page_table_lock);
 799
 800                                 perf_event_mmap(vma);
 801 @@ -2125,6 +2157,8 @@ int expand_downwards(struct vm_area_struct *vma,
 802                                    unsigned long address)
 803  {
 804         struct mm_struct *mm = vma->vm_mm;
 805 +       struct vm_area_struct *prev;
 806 +       unsigned long gap_addr;
 807         int error;
 808
 809         address &= PAGE_MASK;
 810 @@ -2132,6 +2166,17 @@ int expand_downwards(struct vm_area_struct *vma,
 811         if (error)
 812                 return error;
 813
 814 +       /* Enforce stack_guard_gap */
 815 +       gap_addr = address - stack_guard_gap;
 816 +       if (gap_addr > address)
 817 +               return -ENOMEM;
 818 +       prev = vma->vm_prev;
 819 +       if (prev && prev->vm_end > gap_addr) {
 820 +               if (!(prev->vm_flags & VM_GROWSDOWN))
 821 +                       return -ENOMEM;
 822 +               /* Check that both stack segments have the same anon_vma? */
 823 +       }
 824 +
 825         /* We must make sure the anon_vma is allocated. */
 826         if (unlikely(anon_vma_prepare(vma)))
 827                 return -ENOMEM;
 828 @@ -2186,28 +2231,25 @@ int expand_downwards(struct vm_area_struct *vma,
 829         return error;
 830  }
 831
 832 -/*
 833 - * Note how expand_stack() refuses to expand the stack all the way to
 834 - * abut the next virtual mapping, *unless* that mapping itself is also
 835 - * a stack mapping. We want to leave room for a guard page, after all
 836 - * (the guard page itself is not added here, that is done by the
 837 - * actual page faulting logic)
 838 - *
 839 - * This matches the behavior of the guard page logic (see mm/memory.c:
 840 - * check_stack_guard_page()), which only allows the guard page to be
 841 - * removed under these circumstances.
 842 - */
 843 +/* enforced gap between the expanding stack and other mappings. */
 844 +unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
 845 +
 846 +static int __init cmdline_parse_stack_guard_gap(char *p)
 847 +{
 848 +       unsigned long val;
 849 +       char *endptr;
 850 +
 851 +       val = simple_strtoul(p, &endptr, 10);
 852 +       if (!*endptr)
 853 +               stack_guard_gap = val << PAGE_SHIFT;
 854 +
 855 +       return 0;
 856 +}
 857 +__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
 858 +
 859  #ifdef CONFIG_STACK_GROWSUP
 860  int expand_stack(struct vm_area_struct *vma, unsigned long address)
 861  {
 862 -       struct vm_area_struct *next;
 863 -
 864 -       address &= PAGE_MASK;
 865 -       next = vma->vm_next;
 866 -       if (next && next->vm_start == address + PAGE_SIZE) {
 867 -               if (!(next->vm_flags & VM_GROWSUP))
 868 -                       return -ENOMEM;
 869 -       }
 870         return expand_upwards(vma, address);
 871  }
 872
 873 @@ -2229,14 +2271,6 @@ find_extend_vma(struct mm_struct *mm, unsigned long addr)
 874  #else
 875  int expand_stack(struct vm_area_struct *vma, unsigned long address)
 876  {
 877 -       struct vm_area_struct *prev;
 878 -
 879 -       address &= PAGE_MASK;
 880 -       prev = vma->vm_prev;
 881 -       if (prev && prev->vm_end == address) {
 882 -               if (!(prev->vm_flags & VM_GROWSDOWN))
 883 -                       return -ENOMEM;
 884 -       }
 885         return expand_downwards(vma, address);
 886  }
 887
 888 @@ -2334,7 +2368,7 @@ detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
 889                 vma->vm_prev = prev;
 890                 vma_gap_update(vma);
 891         } else
 892 -               mm->highest_vm_end = prev ? prev->vm_end : 0;
 893 +               mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
 894         tail_vma->vm_next = NULL;
 895
 896         /* Kill the cache */
 897 --
 898 2.12.3
 899