Re: [bpf PATCH] bpf: fix uninitialized variable in bpf tools

From: Daniel Borkmann <daniel@iogearbox.net>
To: John Fastabend <john.fastabend@gmail.com>,
	ast@kernel.org, jbenc@redhat.com
Cc: netdev@vger.kernel.org
Subject: Re: [bpf PATCH] bpf: fix uninitialized variable in bpf tools
Date: Thu, 26 Apr 2018 22:55:54 +0200	[thread overview]
Message-ID: <66dea869-f3e3-355d-928a-8894e672b914@iogearbox.net> (raw)
In-Reply-To: <20180425220852.10403.79675.stgit@john-Precision-Tower-5810>

On 04/26/2018 12:08 AM, John Fastabend wrote:
> Here the variable cont is used as the saved_pointer for a call to
> strtok_r(). It is safe to use the value uninitialized in this
> context however and the later reference is only ever used if
> the strtok_r is successful. But, 'gcc-5' at least doesn't have all
> this knowledge so initialize cont to NULL. Additionally, do the
> natural NULL check before accessing just for completness.
> 
> The warning is the following:
> 
> ./bpf/tools/bpf/bpf_dbg.c: In function ‘cmd_load’:
> ./bpf/tools/bpf/bpf_dbg.c:1077:13: warning: ‘cont’ may be used uninitialized in this function [-Wmaybe-uninitialized]
>   } else if (matches(subcmd, "pcap") == 0) {
> 
> Fixes: fd981e3c321a "filter: bpf_dbg: add minimal bpf debugger"
> Signed-off-by: John Fastabend <john.fastabend@gmail.com>

Applied to bpf tree, thanks John!