[PATCH AUTOSEL 6.11 56/87] jfs: fix shift-out-of-bounds in dbSplit

[Sasha Levin]

From: Ghanshyam Agrawal <ghanshyam1898@xxxxxxxxx>

[ Upstream commit a5f5e4698f8abbb25fe4959814093fb5bfa1aa9d ]

When dmt_budmin is less than zero, it causes errors
in the later stages. Added a check to return an error beforehand
in dbAllocCtl itself.

Reported-by: syzbot+b5ca8a249162c4b9a7d0@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=b5ca8a249162c4b9a7d0
Signed-off-by: Ghanshyam Agrawal <ghanshyam1898@xxxxxxxxx>
Signed-off-by: Dave Kleikamp <dave.kleikamp@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/jfs/jfs_dmap.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index 3ab410059dc20..39957361a7eed 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -1820,6 +1820,9 @@ dbAllocCtl(struct bmap * bmp, s64 nblocks, int l2nb, s64 blkno, s64 * results)
 			return -EIO;
 		dp = (struct dmap *) mp->data;
 
+		if (dp->tree.budmin < 0)
+			return -EIO;
+
 		/* try to allocate the blocks.
 		 */
 		rc = dbAllocDmapLev(bmp, dp, (int) nblocks, l2nb, results);
-- 
2.43.0