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@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> Cc: <stable@vger.kernel.org> # v3.0+ Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
e2d0bd2b92
commit
a8f531ebc3
|
@ -2296,6 +2296,8 @@ static void collapse_huge_page(struct mm_struct *mm,
|
||||||
goto out;
|
goto out;
|
||||||
|
|
||||||
vma = find_vma(mm, address);
|
vma = find_vma(mm, address);
|
||||||
|
if (!vma)
|
||||||
|
goto out;
|
||||||
hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
|
hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
|
||||||
hend = vma->vm_end & HPAGE_PMD_MASK;
|
hend = vma->vm_end & HPAGE_PMD_MASK;
|
||||||
if (address < hstart || address + HPAGE_PMD_SIZE > hend)
|
if (address < hstart || address + HPAGE_PMD_SIZE > hend)
|
||||||
|
|
Loading…
Reference in a new issue