netdev - [PATCH 18/32] netfilter: x_tables: don't return garbage pointer on modprobe failure

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Message-Id: <20180119191041.25804-19-pablo@netfilter.org>
Date:   Fri, 19 Jan 2018 20:10:27 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 18/32] netfilter: x_tables: don't return garbage pointer on modprobe failure

From: Florian Westphal <fw@...len.de>

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@...kaller.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@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/x_tables.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index 5b8f3b7358e6..3c2548787d78 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);
 	}
-- 
2.11.0