From: Willem de Bruijn Subject: [PATCH net-next] ip: silence udp zerocopy smatch false positive Date: Sat, 8 Dec 2018 06:22:46 -0500 Message-ID: <20181208112246.16622-1-willemdebruijn.kernel@gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Cc: davem@davemloft.net, Willem de Bruijn To: netdev@vger.kernel.org Return-path: Received: from mail-qk1-f193.google.com ([209.85.222.193]:44065 "EHLO mail-qk1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726111AbeLHLWv (ORCPT ); Sat, 8 Dec 2018 06:22:51 -0500 Received: by mail-qk1-f193.google.com with SMTP id n12so3964643qkh.11 for ; Sat, 08 Dec 2018 03:22:50 -0800 (PST) Sender: netdev-owner@vger.kernel.org List-ID: From: Willem de Bruijn extra_uref is used in __ip(6)_append_data only if uarg is set. Smatch sees that the variable is passed to sock_zerocopy_put_abort. This function accesses it only when uarg is set, but smatch cannot infer this. Make this dependency explicit. Fixes: 52900d22288e ("udp: elide zerocopy operation in hot path") Signed-off-by: Willem de Bruijn --- net/ipv4/ip_output.c | 3 ++- net/ipv6/ip6_output.c | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 78f028bdad30b..ab6618036afed 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -1130,7 +1130,8 @@ static int __ip_append_data(struct sock *sk, error_efault: err = -EFAULT; error: - sock_zerocopy_put_abort(uarg, extra_uref); + if (uarg) + sock_zerocopy_put_abort(uarg, extra_uref); cork->length -= length; IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc); diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 6592a39e5ec10..be25b34dc5c2f 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1575,7 +1575,8 @@ static int __ip6_append_data(struct sock *sk, error_efault: err = -EFAULT; error: - sock_zerocopy_put_abort(uarg, extra_uref); + if (uarg) + sock_zerocopy_put_abort(uarg, extra_uref); cork->length -= length; IP6_INC_STATS(sock_net(sk), rt->rt6i_idev, IPSTATS_MIB_OUTDISCARDS); refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc); -- 2.20.0.rc2.403.gdbc3b29805-goog