netfilter: x_tables: don't return garbage pointer on modprobe failure
request_module may return a positive error result from modprobe,
if we cast this to ERR_PTR this returns a garbage result (it passes
IS_ERR checks).
Fix it by ignoring modprobe return values entirely, just retry the
table lookup instead.
Reported-by: syzbot+980925dbfbc7f93bc2ef@syzkaller.appspotmail.com
Fixes: 03d13b6868a2 ("netfilter: xtables: add and use xt_request_find_table_lock")
Fixes: 20651cefd25f ("netfilter: x_tables: unbreak module auto loading")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index 5b8f3b7..3c25487 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -1085,7 +1085,7 @@ struct xt_table *xt_request_find_table_lock(struct net *net, u_int8_t af,
#ifdef CONFIG_MODULES
if (IS_ERR(t)) {
int err = request_module("%stable_%s", xt_prefix[af], name);
- if (err)
+ if (err < 0)
return ERR_PTR(err);
t = xt_find_table_lock(net, af, name);
}