Re: [syzbot] [bcachefs?] KASAN: null-ptr-deref Read in bch2_sb_set_upgrade_extra

[Jeongjun Park]

#syz test git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

---
 fs/bcachefs/sb-downgrade.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/bcachefs/sb-downgrade.c b/fs/bcachefs/sb-downgrade.c
index ae715ff658e8..8767c33c2b51 100644
--- a/fs/bcachefs/sb-downgrade.c
+++ b/fs/bcachefs/sb-downgrade.c
@@ -143,6 +143,9 @@ UPGRADE_TABLE()
 
 static int have_stripes(struct bch_fs *c)
 {
+	if (IS_ERR_OR_NULL(c->btree_roots_known[BTREE_ID_stripes].b))
+		return 0;
+
 	return !btree_node_fake(c->btree_roots_known[BTREE_ID_stripes].b);
 }
 
--