On 03.01.23 20:53, Suren Baghdasaryan wrote:
On Mon, Jan 2, 2023 at 4:00 AM David Hildenbrand <david@xxxxxxxxxx> wrote:
On 28.12.22 20:42, Suren Baghdasaryan wrote:
free_anon_vma_name() is missing a check for anonymous shmem VMA which
leads to a memory leak due to refcount not being dropped. Fix this by
adding the missing check.
Fixes: d09e8ca6cb93 ("mm: anonymous shared memory naming")
Reported-by: syzbot+91edf9178386a07d06a7@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
---
include/linux/mm_inline.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
index e8ed225d8f7c..d650ca2c5d29 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -413,7 +413,7 @@ static inline void free_anon_vma_name(struct vm_area_struct *vma)
* Not using anon_vma_name because it generates a warning if mmap_lock
* is not held, which might be the case here.
*/
- if (!vma->vm_file)
+ if (!vma->vm_file || vma_is_anon_shmem(vma))
anon_vma_name_put(vma->anon_name);
Wouldn't it be me more consistent to check for "vma->anon_name"?
That's what dup_anon_vma_name() checks. And it's safe now because
anon_name is no longer overloaded in vm_area_struct.
Thanks for the suggestion, David. Yes, with the recent change that
does not overload anon_name, checking for "vma->anon_name" would be
simpler. I think we can also drop anon_vma_name() function now
(https://elixir.bootlin.com/linux/v6.2-rc2/source/mm/madvise.c#L94)
since vma->anon_name does not depend on vma->vm_file anymore, remove
the last part of this comment:
https://elixir.bootlin.com/linux/v6.2-rc2/source/include/linux/mm_types.h#L584
and use vma->anon_name directly going forward. If all that sounds
good, I'll post a separate patch implementing all these changes.
So, for this patch I would suggest keeping it as is because
functionally it is correct and will change this check along with other
corrections I mentioned above in a separate patch. Does that sound
good?
Works for me.
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
for this one, as it fixes the issue.
--
Thanks,
David / dhildenb
