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

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>
Link: https://lore.kernel.org/r/20231009094557.1398920-1-lizhi.xu@windriver.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/jfs/jfs_logmgr.c b/fs/jfs/jfs_logmgr.c
index c911d838b8ec8ceb5d096e879f92c01b8233f65e..cb6d1fda66a7021a9ce5b42959122be9ad1934b2 100644 (file)
--- 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);