From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Gustavo A. R. Silva" Subject: Re: [PATCH 1/2] bpf: sockmap, fix uninitialized variable Date: Thu, 17 May 2018 13:12:43 -0500 Message-ID: <98d55ad8-e5c8-7f1c-ea9b-940be45787d6@embeddedor.com> References: <11073635016901e9e84c2f34f20d412073b26297.1526565461.git.gustavo@embeddedor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: John Fastabend , Alexei Starovoitov , Daniel Borkmann Return-path: Received: from gateway24.websitewelcome.com ([192.185.51.36]:22249 "EHLO gateway24.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751524AbeEQSfb (ORCPT ); Thu, 17 May 2018 14:35:31 -0400 Received: from cm13.websitewelcome.com (cm13.websitewelcome.com [100.42.49.6]) by gateway24.websitewelcome.com (Postfix) with ESMTP id 60CD42D18 for ; Thu, 17 May 2018 13:12:46 -0500 (CDT) In-Reply-To: Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: 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