This is a note to let you know that I've just added the patch titled
mm/huge_memory.c: fix potential NULL pointer dereference
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-huge_memory.c-fix-potential-null-pointer-dereference.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a8f531ebc33052642b4bd7b812eedf397108ce64 Mon Sep 17 00:00:00 2001
From: Libin <huawei.libin@xxxxxxxxxx>
Date: Wed, 11 Sep 2013 14:20:38 -0700
Subject: mm/huge_memory.c: fix potential NULL pointer dereference
From: Libin <huawei.libin@xxxxxxxxxx>
commit a8f531ebc33052642b4bd7b812eedf397108ce64 upstream.
In collapse_huge_page() there is a race window between releasing the
mmap_sem read lock and taking the mmap_sem write lock, so find_vma() may
return NULL. So check the return value to avoid NULL pointer dereference.
collapse_huge_page
khugepaged_alloc_page
up_read(&mm->mmap_sem)
down_write(&mm->mmap_sem)
vma = find_vma(mm, address)
Signed-off-by: Libin <huawei.libin@xxxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reviewed-by: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Michal Hocko <mhocko@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 2 ++
1 file changed, 2 insertions(+)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1894,6 +1894,8 @@ static void collapse_huge_page(struct mm
goto out;
vma = find_vma(mm, address);
+ if (!vma)
+ goto out;
hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
hend = vma->vm_end & HPAGE_PMD_MASK;
if (address < hstart || address + HPAGE_PMD_SIZE > hend)
Patches currently in stable-queue which might be from huawei.libin@xxxxxxxxxx are
queue-3.4/mm-huge_memory.c-fix-potential-null-pointer-dereference.patch
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