netfilter: do not propagate nf_queue errors in nf_hook_slow

commit f15850861860636c905b33a9a5be3dcbc2b0d56a
(netfilter: nfnetlink_queue: return error number to caller)
erronously assigns the return value of nf_queue() to the "ret" value.

This can cause bogus return values if we encounter QUEUE verdict
when bypassing is enabled, the listener does not exist and the
next hook returns NF_STOLEN.

In this case nf_hook_slow returned -ESRCH instead of 0.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 5 insertions, 6 deletions

diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index 3346829ea07f..afca6c78948c 100644
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -180,17 +180,16 @@ next_hook:
                 if (ret == 0)
                         ret = -EPERM;
         } else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) {
-                ret = nf_queue(skb, elem, pf, hook, indev, outdev, okfn,
-                               verdict >> NF_VERDICT_QBITS);
-                if (ret < 0) {
-                        if (ret == -ECANCELED)
+                int err = nf_queue(skb, elem, pf, hook, indev, outdev, okfn,
+                                                verdict >> NF_VERDICT_QBITS);
+                if (err < 0) {
+                        if (err == -ECANCELED)
                                 goto next_hook;
-                        if (ret == -ESRCH &&
+                        if (err == -ESRCH &&
                            (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS))
                                 goto next_hook;
                         kfree_skb(skb);
                 }
-                ret = 0;
         }
         rcu_read_unlock();
         return ret;