linux-kernel - [PATCH v2 1/1] mm: fix vma->anon_name memory leak for anonymous shmem VMAs

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Message-ID: <20230105000241.1450843-1-surenb@google.com>
Date:   Wed,  4 Jan 2023 16:02:40 -0800
From:   Suren Baghdasaryan <surenb@...gle.com>
To:     akpm@...ux-foundation.org
Cc:     hughd@...gle.com, hannes@...xchg.org, david@...hat.com,
        vincent.whitchurch@...s.com, seanjc@...gle.com, rppt@...nel.org,
        shy828301@...il.com, pasha.tatashin@...een.com,
        paul.gortmaker@...driver.com, peterx@...hat.com, vbabka@...e.cz,
        Liam.Howlett@...cle.com, ccross@...gle.com, willy@...radead.org,
        arnd@...db.de, cgel.zte@...il.com, yuzhao@...gle.com,
        bagasdotme@...il.com, suleiman@...gle.com, steven@...uorix.net,
        heftig@...hlinux.org, cuigaosheng1@...wei.com,
        kirill@...temov.name, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        surenb@...gle.com,
        syzbot+91edf9178386a07d06a7@...kaller.appspotmail.com
Subject: [PATCH v2 1/1] mm: fix vma->anon_name memory leak for anonymous shmem VMAs

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
calling anon_vma_name_put() unconditionally. It will free vma->anon_name
whenever it's non-NULL.

Fixes: d09e8ca6cb93 ("mm: anonymous shared memory naming")
Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
Suggested-by: David Hildenbrand <david@...hat.com>
Reported-by: syzbot+91edf9178386a07d06a7@...kaller.appspotmail.com
Cc: David Hildenbrand <david@...hat.com>
Cc: Hugh Dickins <hughd@...gle.com>
Cc: Pasha Tatashin <pasha.tatashin@...een.com>
---
applies over mm-hotfixes-unstable branch of
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm tree after reverting
the original version of this patch.

 include/linux/mm_inline.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
index e8ed225d8f7c..ff3f3f23f649 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -413,8 +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)
-		anon_vma_name_put(vma->anon_name);
+	anon_vma_name_put(vma->anon_name);
 }
 
 static inline bool anon_vma_name_eq(struct anon_vma_name *anon_name1,
-- 
2.39.0.314.g84b9a713c41-goog