linux-kernel - [PATCH] bcachefs: return err ptr instead of null in read sb clean

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20240910211912.96356-1-djahchankoike@gmail.com>
Date: Tue, 10 Sep 2024 18:18:34 -0300
From: Diogo Jahchan Koike <djahchankoike@...il.com>
To: Kent Overstreet <kent.overstreet@...ux.dev>
Cc: Diogo Jahchan Koike <djahchankoike@...il.com>,
	syzbot+1cecc37d87c4286e5543@...kaller.appspotmail.com,
	linux-bcachefs@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] bcachefs: return err ptr instead of null in read sb clean

syzbot reported a null-ptr-deref in bch2_fs_start. [0]

When a sb is marked clear but doesn't have a clean section
bch2_read_superblock_clean returns NULL which PTR_ERR_OR_ZERO
lets through, eventually leading to a null ptr dereference down
the line. Adjust read sb clean to return an ERR_PTR indicating the
invalid clean section.

[0] https://syzkaller.appspot.com/bug?extid=1cecc37d87c4286e5543

Reported-by: syzbot+1cecc37d87c4286e5543@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=1cecc37d87c4286e5543
Signed-off-by: Diogo Jahchan Koike <djahchankoike@...il.com>
---
 fs/bcachefs/sb-clean.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/bcachefs/sb-clean.c b/fs/bcachefs/sb-clean.c
index c57d42bb8d1b..025848a9c4c0 100644
--- a/fs/bcachefs/sb-clean.c
+++ b/fs/bcachefs/sb-clean.c
@@ -155,7 +155,7 @@ struct bch_sb_field_clean *bch2_read_superblock_clean(struct bch_fs *c)
 		SET_BCH_SB_CLEAN(c->disk_sb.sb, false);
 		c->sb.clean = false;
 		mutex_unlock(&c->sb_lock);
-		return NULL;
+		return ERR_PTR(-BCH_ERR_invalid_sb_clean);
 	}
 
 	clean = kmemdup(sb_clean, vstruct_bytes(&sb_clean->field),
-- 
2.43.0