From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751977AbeEQS7g (ORCPT ); Thu, 17 May 2018 14:59:36 -0400 Received: from gateway36.websitewelcome.com ([192.185.196.23]:48550 "EHLO gateway36.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751695AbeEQS7f (ORCPT ); Thu, 17 May 2018 14:59:35 -0400 X-Authority-Reason: nr=8 Subject: Re: [PATCH 1/2] bpf: sockmap, fix uninitialized variable To: John Fastabend , Alexei Starovoitov , Daniel Borkmann Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <11073635016901e9e84c2f34f20d412073b26297.1526565461.git.gustavo@embeddedor.com> From: "Gustavo A. R. Silva" Message-ID: <98d55ad8-e5c8-7f1c-ea9b-940be45787d6@embeddedor.com> Date: Thu, 17 May 2018 13:12:43 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 187.172.56.86 X-Source-L: No X-Exim-ID: 1fJNOP-003gk1-Vs X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: ([192.168.1.70]) [187.172.56.86]:42258 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 10 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi John, On 05/17/2018 12:27 PM, John Fastabend wrote: > On 05/17/2018 07:08 AM, Gustavo A. R. Silva wrote: >> There is a potential execution path in which variable err is >> returned without being properly initialized previously. >> >> Fix this by initializing variable err to 0. >> >> Addresses-Coverity-ID: 1468964 ("Uninitialized scalar variable") >> Fixes: e5cd3abcb31a ("bpf: sockmap, refactor sockmap routines to work >> with hashmap") >> Signed-off-by: Gustavo A. R. Silva >> --- >> kernel/bpf/sockmap.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c >> index c6de139..41b41fc 100644 >> --- a/kernel/bpf/sockmap.c >> +++ b/kernel/bpf/sockmap.c >> @@ -1713,7 +1713,7 @@ static int __sock_map_ctx_update_elem(struct bpf_map *map, >> struct smap_psock_map_entry *e = NULL; >> struct smap_psock *psock; >> bool new = false; >> - int err; >> + int err = 0; >> >> /* 1. If sock map has BPF programs those will be inherited by the >> * sock being added. If the sock is already attached to BPF programs >> > > Thanks for catching this and the quick fix. The path to hit this case > is to add a sock to a map (without a BPF program) where the sock already > has been added to another map. I don't have any tests for the case with > socks in multiple maps so I'll add some to the selftests so I remember > this case. > Glad to help. :) > The alternative fix would be to always 'return 0' at the end of the > function, but I think its probably better to init err here like above. > Yeah. I think initializing err is better in this case. > Acked-by: John Fastabend > Thank you -- Gustavo