Subject: + mm-fix-potential-null-pointer-dereference.patch added to -mm tree
To: huawei.libin@xxxxxxxxxx,kirill.shutemov@xxxxxxxxxxxxxxx,liwanp@xxxxxxxxxxxxxxxxxx,mhocko@xxxxxxx,stable@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Fri, 26 Jul 2013 14:39:41 -0700
The patch titled
Subject: mm/huge_memory.c: fix potential NULL pointer dereference
has been added to the -mm tree. Its filename is
mm-fix-potential-null-pointer-dereference.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-fix-potential-null-pointer-dereference.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-fix-potential-null-pointer-dereference.patch
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------------------------------------------------------
From: Libin <huawei.libin@xxxxxxxxxx>
Subject: mm/huge_memory.c: fix potential NULL pointer dereference
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>
Cc: <stable@xxxxxxxxxxxxxxx> # v3.0+
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 2 ++
1 file changed, 2 insertions(+)
diff -puN mm/huge_memory.c~mm-fix-potential-null-pointer-dereference mm/huge_memory.c
--- a/mm/huge_memory.c~mm-fix-potential-null-pointer-dereference
+++ a/mm/huge_memory.c
@@ -2274,6 +2274,8 @@ 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 -mm which might be from huawei.libin@xxxxxxxxxx are
mm-fix-potential-null-pointer-dereference.patch
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