Re: [PATCH 1/1] mm: fix vma->anon_name memory leak for anonymous shmem VMAs

[David Hildenbrand]

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,

David / dhildenb