From patchwork Tue Oct 11 15:39:21 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [3/3] vm: fix vm_pgoff wrap in upward expansion - CVE-2011-2496 From: Paolo Pisati X-Patchwork-Id: 119000 Message-Id: <1318347561-1410-4-git-send-email-paolo.pisati@canonical.com> To: kernel-team@lists.ubuntu.com Date: Tue, 11 Oct 2011 17:39:21 +0200 Commit a626ca6a6564 ("vm: fix vm_pgoff wrap in stack expansion") fixed the case of an expanding mapping causing vm_pgoff wrapping when you had downward stack expansion. But there was another case where IA64 and PA-RISC expand mappings: upward expansion. This fixes that case too. Signed-off-by: Hugh Dickins Cc: stable@kernel.org Signed-off-by: Linus Torvalds CVE-2011-2496 BugLink: http://bugs.launchpad.net/bugs/869243 commit upstream a626ca6a656450e9f4df91d0dda238fff23285f4 Signed-off-by: Paolo Pisati --- mm/mmap.c | 9 ++++++--- 1 files changed, 6 insertions(+), 3 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 1508d86..027108e 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1735,9 +1735,12 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address) size = address - vma->vm_start; grow = (address - vma->vm_end) >> PAGE_SHIFT; - error = acct_stack_growth(vma, size, grow); - if (!error) - vma->vm_end = address; + error = -ENOMEM; + if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) { + error = acct_stack_growth(vma, size, grow); + if (!error) + vma->vm_end = address; + } } anon_vma_unlock(vma); return error;