shm: fix null pointer deref when userspace specifies invalid hugepage size
authorLi Zefan <lizefan@huawei.com>
Thu, 9 May 2013 07:08:15 +0000 (15:08 +0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 9 May 2013 21:22:47 +0000 (14:22 -0700)
commit091d0d55b286c9340201b4ed4470be87fc568228
tree5417ab8864fbabe1a9931f3a9a81355cd3d3ebaa
parentde2657f94acd4f0df44626db7c4d2b71babc8cd3
shm: fix null pointer deref when userspace specifies invalid hugepage size

Dave reported an oops triggered by trinity:

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
  IP: newseg+0x10d/0x390
  PGD cf8c1067 PUD cf8c2067 PMD 0
  Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
  CPU: 2 PID: 7636 Comm: trinity-child2 Not tainted 3.9.0+#67
  ...
  Call Trace:
    ipcget+0x182/0x380
    SyS_shmget+0x5a/0x60
    tracesys+0xdd/0xe2

This bug was introduced by commit af73e4d9506d ("hugetlbfs: fix mmap
failure in unaligned size request").

Reported-by: Dave Jones <davej@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Li Zefan <lizfan@huawei.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
ipc/shm.c
mm/mmap.c