lkml.org 
[lkml]   [2011]   [Apr]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[064/105] mm: avoid wrapping vm_pgoff in mremap()
    2.6.38-stable review patch.  If anyone has any objections, please let us know.

    ------------------

    From: Linus Torvalds <torvalds@linux-foundation.org>

    commit 982134ba62618c2d69fbbbd166d0a11ee3b7e3d8 upstream.

    The normal mmap paths all avoid creating a mapping where the pgoff
    inside the mapping could wrap around due to overflow. However, an
    expanding mremap() can take such a non-wrapping mapping and make it
    bigger and cause a wrapping condition.

    Noticed by Robert Swiecki when running a system call fuzzer, where it
    caused a BUG_ON() due to terminally confusing the vma_prio_tree code. A
    vma dumping patch by Hugh then pinpointed the crazy wrapped case.

    Reported-and-tested-by: Robert Swiecki <robert@swiecki.net>
    Acked-by: Hugh Dickins <hughd@google.com>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    mm/mremap.c | 11 +++++++++--
    1 file changed, 9 insertions(+), 2 deletions(-)

    --- a/mm/mremap.c
    +++ b/mm/mremap.c
    @@ -277,9 +277,16 @@ static struct vm_area_struct *vma_to_res
    if (old_len > vma->vm_end - addr)
    goto Efault;

    - if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) {
    - if (new_len > old_len)
    + /* Need to be careful about a growing mapping */
    + if (new_len > old_len) {
    + unsigned long pgoff;
    +
    + if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
    goto Efault;
    + pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
    + pgoff += vma->vm_pgoff;
    + if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
    + goto Einval;
    }

    if (vma->vm_flags & VM_LOCKED) {



    \
     
     \ /
      Last update: 2011-04-12 17:05    [W:4.493 / U:0.056 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site