diff options
| author | Libin <huawei.libin@huawei.com> | 2013-09-11 14:20:38 -0700 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2013-10-26 21:06:03 +0100 |
| commit | 56cbe7f7ee88a2eb06226ab3b5b4333fe0df663f (patch) | |
| tree | f8535ed6256cf152fb95324cd499a3552ae14817 | |
| parent | 89b2cd31a07fcee833fd0284eaeb7d57419a698f (diff) | |
| download | lwn-56cbe7f7ee88a2eb06226ab3b5b4333fe0df663f.tar.gz lwn-56cbe7f7ee88a2eb06226ab3b5b4333fe0df663f.zip | |
mm/huge_memory.c: fix potential NULL pointer dereference
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@huawei.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | mm/huge_memory.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index d80ac4bb0971..ed0ed8a41fba 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1882,6 +1882,8 @@ static void collapse_huge_page(struct mm_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) |