[PATCH v5 2/2] ocfs2: Fix possible null-ptr-deref in ocfs2_set_buffer_uptodate

[Joseph Qi]

From: Lizhi Xu <lizhi.xu@xxxxxxxxxxxxx>

When doing cleanup, if flags without OCFS2_BH_READAHEAD, it may trigger
NULL pointer dereference in the following ocfs2_set_buffer_uptodate() if
bh is NULL.

Reported-and-suggested-by: Heming Zhao <heming.zhao@xxxxxxxx>
Fixes: cf76c78595ca ("ocfs2: don't put and assigning null to bh allocated outside")
Cc: stable@xxxxxxxxxxxxxxx # 4.20+
Signed-off-by: Lizhi Xu <lizhi.xu@xxxxxxxxxxxxx>
Reviewed-by: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
Signed-off-by: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
---
 fs/ocfs2/buffer_head_io.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/ocfs2/buffer_head_io.c b/fs/ocfs2/buffer_head_io.c
index e62c7e1de4eb..8f714406528d 100644
--- a/fs/ocfs2/buffer_head_io.c
+++ b/fs/ocfs2/buffer_head_io.c
@@ -388,7 +388,8 @@ int ocfs2_read_blocks(struct ocfs2_caching_info *ci, u64 block, int nr,
 		/* Always set the buffer in the cache, even if it was
 		 * a forced read, or read-ahead which hasn't yet
 		 * completed. */
-		ocfs2_set_buffer_uptodate(ci, bh);
+		if (bh)
+			ocfs2_set_buffer_uptodate(ci, bh);
 	}
 	ocfs2_metadata_cache_io_unlock(ci);
 
-- 
2.39.3