UBSAN: array-index-out-of-bounds in dtInsertEntry

[Ghanshyam Agrawal]

#syz test
From bdc956a38762cda97b69b164f55cdb94f6f9cbe3 Mon Sep 17 00:00:00 2001
From: Ghanshyam Agrawal <ghanshyam1898@xxxxxxxxx>
Date: Thu, 10 Oct 2024 18:36:43 +0530
Subject: [PATCH] jfs: fix array-index-out-of-bounds in dtInsertEntry
To: shaggy@xxxxxxxxxx,
    osmtendev@xxxxxxxxx,
    ghandatmanas@xxxxxxxxx,
    eadavis@xxxxxx,
    ghanshyam1898@xxxxxxxxx
Cc: jfs-discussion@xxxxxxxxxxxxxxxxxxxxx,
    linux-kernel@xxxxxxxxxxxxxxx

The value of p->header.freelist can be less than zero which
causes an error in dtInsertEntry. Added a check in dtInsert
to address it.

Reported-by: syzbot+5f7f0caf9979e9d09ff8@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=5f7f0caf9979e9d09ff8
Signed-off-by: Ghanshyam Agrawal <ghanshyam1898@xxxxxxxxx>
---
 fs/jfs/jfs_dtree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/jfs/jfs_dtree.c b/fs/jfs/jfs_dtree.c
index 5d3127ca68a4..51bb3e14551b 100644
--- a/fs/jfs/jfs_dtree.c
+++ b/fs/jfs/jfs_dtree.c
@@ -834,7 +834,7 @@ int dtInsert(tid_t tid, struct inode *ip,
 	 * the full page.
 	 */
 	DT_GETSEARCH(ip, btstack->top, bn, mp, p, index);
-	if (p->header.freelist == 0)
+	if (p->header.freelist <= 0)
 		return -EINVAL;
 
 	/*
-- 
2.34.1