Re: [syzbot] general protection fault in bch2_fs_recovery

[syzbot <syzbot+1cecc37d87c4286e5543@syzkaller.appspotmail.com>]

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Subject: general protection fault in bch2_fs_recovery
Author: djahchankoike@gmail.com

#syz test

When a sb is marked clean but doesn't have a clean section
bch2_read_superblock_clean returns NULL which PTR_ERR_OR_ZERO
lets through (returns 0), eventually leading to a null ptr
dereference down the line. Adjust read sb clean to return an
ERR_PTR indicating the invalid clean section.

Signed-off-by: Diogo Jahchan Koike <djahchankoike@gmail.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