From 63c3b902e517012b127d6528434b928ceaa10f7b Mon Sep 17 00:00:00 2001 From: Michel Lespinasse Date: Fri, 16 Nov 2012 14:14:47 -0800 Subject: [PATCH] mm: add anon_vma_lock to validate_mm() Iterating over the vma->anon_vma_chain without anon_vma_lock may cause NULL ptr deref in anon_vma_interval_tree_verify(), because the node in the chain might have been removed. BUG: unable to handle kernel paging request at fffffffffffffff0 IP: [] anon_vma_interval_tree_verify+0xc/0xa0 PGD 4e28067 PUD 4e29067 PMD 0 Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC CPU 0 Pid: 9050, comm: trinity-child64 Tainted: G W 3.7.0-rc2-next-20121025-sasha-00001-g673f98e-dirty #77 RIP: 0010: anon_vma_interval_tree_verify+0xc/0xa0 Process trinity-child64 (pid: 9050, threadinfo ffff880045f80000, task ffff880048eb0000) Call Trace: validate_mm+0x58/0x1e0 vma_adjust+0x635/0x6b0 __split_vma.isra.22+0x161/0x220 split_vma+0x24/0x30 sys_madvise+0x5da/0x7b0 tracesys+0xe1/0xe6 RIP anon_vma_interval_tree_verify+0xc/0xa0 CR2: fffffffffffffff0 Figured out by Bob Liu. Reported-by: Sasha Levin Cc: Bob Liu Signed-off-by: Michel Lespinasse Reviewed-by: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mmap.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/mmap.c b/mm/mmap.c index 2d942353d68..9a796c41e7d 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -334,8 +334,10 @@ void validate_mm(struct mm_struct *mm) struct vm_area_struct *vma = mm->mmap; while (vma) { struct anon_vma_chain *avc; + vma_lock_anon_vma(vma); list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) anon_vma_interval_tree_verify(avc); + vma_unlock_anon_vma(vma); vma = vma->vm_next; i++; } -- 2.20.1