From 56a62e2218f544258bd1796889a42f4516ccd04a Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Tue, 8 Nov 2016 14:28:19 +0100 Subject: [PATCH] netfilter: conntrack: fix NF_REPEAT handling gcc correctly identified a theoretical uninitialized variable use: net/netfilter/nf_conntrack_core.c: In function 'nf_conntrack_in': net/netfilter/nf_conntrack_core.c:1125:14: error: 'l4proto' may be used uninitialized in this function [-Werror=maybe-uninitialized] This could only happen when we 'goto out' before looking up l4proto, and then enter the retry, implying that l3proto->get_l4proto() returned NF_REPEAT. This does not currently get returned in any code path and probably won't ever happen, but is not good to rely on. Moving the repeat handling up a little should have the same behavior as today but avoids the warning by making that case impossible to enter. [ I have mangled this original patch to remove the check for tmpl, we should inconditionally jump back to the repeat label in case we hit NF_REPEAT instead. I have also moved the comment that explains this where it belongs. --pablo ] Fixes: 08733a0cb7de ("netfilter: handle NF_REPEAT from nf_conntrack_in()") Signed-off-by: Arnd Bergmann Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_core.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index de4b8a75f30b..e9ffe33dc0ca 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -1337,6 +1337,12 @@ repeat: NF_CT_STAT_INC_ATOMIC(net, invalid); if (ret == -NF_DROP) NF_CT_STAT_INC_ATOMIC(net, drop); + /* Special case: TCP tracker reports an attempt to reopen a + * closed/aborted connection. We have to go back and create a + * fresh conntrack. + */ + if (ret == -NF_REPEAT) + goto repeat; ret = -ret; goto out; } @@ -1344,16 +1350,8 @@ repeat: if (set_reply && !test_and_set_bit(IPS_SEEN_REPLY_BIT, &ct->status)) nf_conntrack_event_cache(IPCT_REPLY, ct); out: - if (tmpl) { - /* Special case: TCP tracker reports an attempt to reopen a - * closed/aborted connection. We have to go back and create a - * fresh conntrack. - */ - if (ret == NF_REPEAT) - goto repeat; - else - nf_ct_put(tmpl); - } + if (tmpl) + nf_ct_put(tmpl); return ret; } -- 2.20.1