[PATCH] jfs: fix log->bdev_handle null ptr deref in lbmStartIO

From: Lizhi Xu <lizhi.xu@windriver.com>
To: <syzbot+23bc20037854bb335d59@syzkaller.appspotmail.com>
Cc: <axboe@kernel.dk>, <brauner@kernel.org>,
	<dave.kleikamp@oracle.com>, <hare@suse.de>, <hch@lst.de>,
	<jack@suse.cz>, <jfs-discussion@lists.sourceforge.net>,
	<johannes.thumshirn@wdc.com>, <linux-fsdevel@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <shaggy@kernel.org>,
	<syzkaller-bugs@googlegroups.com>
Subject: [PATCH] jfs: fix log->bdev_handle null ptr deref in lbmStartIO
Date: Mon, 9 Oct 2023 17:45:57 +0800	[thread overview]
Message-ID: <20231009094557.1398920-1-lizhi.xu@windriver.com> (raw)
In-Reply-To: <0000000000005239cf060727d3f6@google.com>

When sbi->flag is JFS_NOINTEGRITY in lmLogOpen(), log->bdev_handle can't
be inited, so it value will be NULL.
Therefore, add the "log ->no_integrity=1" judgment in lbmStartIO() to avoid such
problems.

Reported-and-tested-by: syzbot+23bc20037854bb335d59@syzkaller.appspotmail.com
Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com>
---
 fs/jfs/jfs_logmgr.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/jfs/jfs_logmgr.c b/fs/jfs/jfs_logmgr.c
index c911d838b8ec..c41a76164f84 100644
--- a/fs/jfs/jfs_logmgr.c
+++ b/fs/jfs/jfs_logmgr.c
@@ -2110,10 +2110,14 @@ static void lbmStartIO(struct lbuf * bp)
 {
 	struct bio *bio;
 	struct jfs_log *log = bp->l_log;
+	struct block_device *bdev = NULL;
 
 	jfs_info("lbmStartIO");
 
-	bio = bio_alloc(log->bdev_handle->bdev, 1, REQ_OP_WRITE | REQ_SYNC,
+	if (!log->no_integrity) 
+		bdev = log->bdev_handle->bdev;	
+
+	bio = bio_alloc(bdev, 1, REQ_OP_WRITE | REQ_SYNC,
 			GFP_NOFS);
 	bio->bi_iter.bi_sector = bp->l_blkno << (log->l2bsize - 9);
 	__bio_add_page(bio, bp->l_page, LOGPSIZE, bp->l_offset);
-- 
2.25.1

