Re: [syzbot] Re: [syzbot] [jfs?] KASAN: null-ptr-deref Read in drop_buffers (3)

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Subject: Re: [syzbot] [jfs?] KASAN: null-ptr-deref Read in drop_buffers (3)
Author: richard120310@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git cb82ca153949

Signed-off-by: I Hsin Cheng <richard120310@gmail.com>
---
 fs/buffer.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index cc8452f60251..1e3a07c66c1a 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2885,7 +2885,7 @@ drop_buffers(struct folio *folio, struct buffer_head **buffers_to_free)
 
 	bh = head;
 	do {
-		if (buffer_busy(bh))
+		if (!bh || buffer_busy(bh))
 			goto failed;
 		bh = bh->b_this_page;
 	} while (bh != head);
@@ -2896,6 +2896,8 @@ drop_buffers(struct folio *folio, struct buffer_head **buffers_to_free)
 		if (bh->b_assoc_map)
 			__remove_assoc_queue(bh);
 		bh = next;
+		if (!bh)
+			goto failed;
 	} while (bh != head);
 	*buffers_to_free = head;
 	folio_detach_private(folio);
-- 
2.43.0