From: Alexei Filippov <halip0503@gmail.com>
Date: Sat, 19 Aug 2023 17:32:16 +0000 (+0300)
Subject: jfs: validate max amount of blocks before allocation.
X-Git-Tag: v6.6-rc1~110^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0225e10972fa809728b8d4c1bd2772b3ec3fdb57;p=thirdparty%2Fkernel%2Flinux.git

jfs: validate max amount of blocks before allocation.

The lack of checking bmp->db_max_freebud in extBalloc() can lead to
shift out of bounds, so this patch prevents undefined behavior, because
bmp->db_max_freebud == -1 only if there is no free space.

Signed-off-by: Aleksei Filippov <halip0503@gmail.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-and-tested-by: syzbot+5f088f29593e6b4c8db8@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?id=01abadbd6ae6a08b1f1987aa61554c6b3ac19ff2
---

diff --git a/fs/jfs/jfs_extent.c b/fs/jfs/jfs_extent.c
index adaa9ad50d4c8..63d21822d309b 100644
--- a/fs/jfs/jfs_extent.c
+++ b/fs/jfs/jfs_extent.c
@@ -311,6 +311,11 @@ extBalloc(struct inode *ip, s64 hint, s64 * nblocks, s64 * blkno)
 	 * blocks in the map. in that case, we'll start off with the
 	 * maximum free.
 	 */
+
+	/* give up if no space left */
+	if (bmp->db_maxfreebud == -1)
+		return -ENOSPC;
+
 	max = (s64) 1 << bmp->db_maxfreebud;
 	if (*nblocks >= max && *nblocks > nbperpage)
 		nb = nblks = (max > nbperpage) ? max : nbperpage;