linux-kernel - [PATCH] hfs: Prevent the use of bnodes without entries

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Message-ID: <tencent_DFFF86C192DEC64EC99B6EF96EDE4C986706@qq.com>
Date: Thu, 24 Jul 2025 23:08:26 +0800
From: Edward Adam Davis <eadavis@...com>
To: syzbot+41ba9c82bce8d7101765@...kaller.appspotmail.com
Cc: frank.li@...o.com,
	glaubitz@...sik.fu-berlin.de,
	linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	slava@...eyko.com,
	syzkaller-bugs@...glegroups.com
Subject: [PATCH] hfs: Prevent the use of bnodes without entries

If the number of entries in the bnode is 0, the bnode is considered
invalid.

Reported-by: syzbot+41ba9c82bce8d7101765@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=41ba9c82bce8d7101765
Tested-by: syzbot+41ba9c82bce8d7101765@...kaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@...com>
---
 fs/hfs/bfind.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/hfs/bfind.c b/fs/hfs/bfind.c
index ef9498a6e88a..1d6f2bbafa7a 100644
--- a/fs/hfs/bfind.c
+++ b/fs/hfs/bfind.c
@@ -133,6 +133,8 @@ int hfs_brec_find(struct hfs_find_data *fd)
 			goto invalid;
 		if (bnode->type != (--height ? HFS_NODE_INDEX : HFS_NODE_LEAF))
 			goto invalid;
+		if (!bnode->num_recs)
+			goto invalid;
 		bnode->parent = parent;
 
 		res = __hfs_brec_find(bnode, fd);
-- 
2.43.0