Re: [PATCH] rtla/osnoise: fix NULL but dereferenced coccicheck errors

From: Jiabing Wan <wanjiabing@vivo.com>
To: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: kael_w@qq.com, Steven Rostedt <rostedt@goodmis.org>,
	linux-trace-devel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] rtla/osnoise: fix NULL but dereferenced coccicheck errors
Date: Fri, 1 Apr 2022 10:04:16 +0800	[thread overview]
Message-ID: <35ceefc3-3f8c-f3aa-e468-1f21161f920b@vivo.com> (raw)
In-Reply-To: <2afd6cba-1a01-0c32-eae8-c4f9f7e76732@kernel.org>

Hi Daniel,

On 2022/3/31 20:25, Daniel Bristot de Oliveira wrote:
> Hi Wan
>
> On 3/22/22 12:32, Wan Jiabing wrote:
>> Fix the following coccicheck errors:
>> ./tools/tracing/rtla/src/osnoise_hist.c:870:31-36: ERROR: record is NULL but dereferenced.
>> ./tools/tracing/rtla/src/osnoise_top.c:650:31-36: ERROR: record is NULL but dereferenced.
>>
>> "record" is NULL before calling osnoise_init_trace_tool.
>> Add a tag "out_free" to avoid dereferring a NULL pointer.
> Yes, I see the problem.
>
> Please, change the Subject to something with better information about the
> problem, instead of the way you fund it.
OK, I'll fix it.

>> Fixes: 51d64c3a1819 ("rtla: Add -e/--event support")
>> Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
>> ---
>>   tools/tracing/rtla/src/osnoise_hist.c | 5 +++--
>>   tools/tracing/rtla/src/osnoise_top.c  | 9 +++++----
>>   2 files changed, 8 insertions(+), 6 deletions(-)
> Please, also add the version of coccicheck you are using, because it seems that
> there is a problem with it. There is a similar problem with timerlat, added by
> the same patch, but it seems that coccicheck did not find it.
>
> Would you mind to check coccicheck, and also add the fix for timerlat?

Yes,  I used null/deref_null.cocci to report these warnings. But there 
were no warnings in
timerlat. So I check the null/deref_null.cocci and modify some rules.

Using modified null/deref_null.cocci, there are warnings as follow:

tools/tracing/rtla/src/timerlat_hist.c:905:31-36: ERROR: record is NULL 
but dereferenced.
tools/tracing/rtla/src/osnoise_top.c:650:31-36: ERROR: record is NULL 
but dereferenced.
tools/tracing/rtla/src/osnoise_hist.c:870:31-36: ERROR: record is NULL 
but dereferenced.
tools/tracing/rtla/src/timerlat_top.c:700:31-36: ERROR: record is NULL 
but dereferenced.

I'll resend the patch and fix them all.

Thanks,
Wan Jiabing
> Thanks.
> -- Daniel
>