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

On Mon, 09 Oct 2023 17:45:57 +0800, Lizhi Xu wrote:
> 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.
> 
> 

Applied to the vfs.super branch of the vfs/vfs.git tree.
Patches in the vfs.super branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs.super

[1/1] jfs: fix log->bdev_handle null ptr deref in lbmStartIO
      https://git.kernel.org/vfs/vfs/c/dc869ef84f26

On Mon 09-10-23 17:45:57, Lizhi Xu wrote:
> 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>

Ah, good catch. Who would think someone creates bios for NULL bdev only to
release them shortly afterwards ;). Anyway the fix looks good. Feel free to
add:

Reviewed-by: Jan Kara <jack@suse.cz>

Christian, please pick up this fixup into your tree. Thanks!

								Honza

> ---
>  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
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

> Christian, please pick up this fixup into your tree. Thanks!

Done!