From 664b8ee764c295ff3bfd9736094a036dcc0ebda2 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Tue, 6 Jan 2009 14:40:31 -0800 Subject: mm: check for no mmaps in exit_mmap() commit dcd4a049b9751828c516c59709f3fdf50436df85 upstream. When dup_mmap() ooms we can end up with mm->mmap == NULL. The error path does mmput() and unmap_vmas() gets a NULL vma which it dereferences. In exit_mmap() there is nothing to do at all for this case, we can cancel the callpath right there. [akpm@linux-foundation.org: add sorely-needed comment] Signed-off-by: Johannes Weiner Reported-by: Akinobu Mita Cc: Nick Piggin Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Reported-by: Kir Kolyshkin Tested-by: Kir Kolyshkin Signed-off-by: Greg Kroah-Hartman --- mm/mmap.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/mmap.c b/mm/mmap.c index ca12a9308436..2ae093ed2cac 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2068,6 +2068,9 @@ void exit_mmap(struct mm_struct *mm) arch_exit_mmap(mm); mmu_notifier_release(mm); + if (!mm->mmap) /* Can happen if dup_mmap() received an OOM */ + return; + lru_add_drain(); flush_cache_mm(mm); tlb = tlb_gather_mmu(mm, 1); -- cgit v1.2.3