linux-kernel - [PATCH v5 2/2] ocfs2: Fix possible null-ptr-deref in ocfs2_set_buffer

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Message-Id: <20240902023636.1843422-3-joseph.qi@linux.alibaba.com>
Date: Mon,  2 Sep 2024 10:36:36 +0800
From: Joseph Qi <joseph.qi@...ux.alibaba.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
	Lizhi Xu <lizhi.xu@...driver.com>,
	Heming Zhao <heming.zhao@...e.com>
Cc: ocfs2-devel@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	jlbec@...lplan.org,
	mark@...heh.com,
	syzbot+ab134185af9ef88dfed5@...kaller.appspotmail.com,
	syzkaller-bugs@...glegroups.com
Subject: [PATCH v5 2/2] ocfs2: Fix possible null-ptr-deref in ocfs2_set_buffer_uptodate

From: Lizhi Xu <lizhi.xu@...driver.com>

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@...e.com>
Fixes: cf76c78595ca ("ocfs2: don't put and assigning null to bh allocated outside")
Cc: stable@...r.kernel.org # 4.20+
Signed-off-by: Lizhi Xu <lizhi.xu@...driver.com>
Reviewed-by: Joseph Qi <joseph.qi@...ux.alibaba.com>
Signed-off-by: Joseph Qi <joseph.qi@...ux.alibaba.com>
---
 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