linux-kernel - Re: [syzbot] general protection fault in __copy

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Message-ID: <66f1d868.050a0220.c23dd.0017.GAE@google.com>
Date: Mon, 23 Sep 2024 14:06:48 -0700
From: syzbot <syzbot+18a5c5e8a9c856944876@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org
Subject: Re: [syzbot] general protection fault in __copy_super

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linux-kernel@...r.kernel.org.

***

Subject: general protection fault in __copy_super
Author: djahchankoike@...il.com

#syz test

__bch2_read_super may return no error code when a corrupt backup
superblock has matching offsets with default opts, the superblock
is freed and is later dereferenced causing a fault. Assign EINVALID
when checking sb offsets.

Signed-off-by: Diogo Jahchan Koike <djahchankoike@...il.com>
---
 fs/bcachefs/super-io.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/bcachefs/super-io.c b/fs/bcachefs/super-io.c
index c8c2ccbdfbb5..fbca0bd302db 100644
--- a/fs/bcachefs/super-io.c
+++ b/fs/bcachefs/super-io.c
@@ -796,8 +796,10 @@ static int __bch2_read_super(const char *path, struct bch_opts *opts,
 	     i < layout.sb_offset + layout.nr_superblocks; i++) {
 		offset = le64_to_cpu(*i);
 
-		if (offset == opt_get(*opts, sb))
+		if (offset == opt_get(*opts, sb)) {
+			ret = -BCH_ERR_invalid;
 			continue;
+		}
 
 		ret = read_one_super(sb, offset, &err);
 		if (!ret)
-- 
2.43.0