Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Subject: Re: [PATCH v2] livepatch: Reorder to use before freeing a pointer
To:     Petr Mladek <pmladek@suse.com>
Cc:     jpoimboe@redhat.com, jikos@kernel.org, mbenes@suse.cz,
        joe.lawrence@redhat.com, nathan@kernel.org,
        ndesaulniers@google.com, live-patching@vger.kernel.org,
        linux-kernel@vger.kernel.org, llvm@lists.linux.dev
References: <20220320015143.2208591-1-trix@redhat.com>
 <YjtCY1QaA6GI3b+7@alley>
From:   Tom Rix <trix@redhat.com>
Message-ID: <be3ac729-8d1d-0c2e-6d63-aeb23ca04bbd@redhat.com>
Date:   Wed, 23 Mar 2022 09:17:35 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.10.1
MIME-Version: 1.0
In-Reply-To: <YjtCY1QaA6GI3b+7@alley>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
Content-Language: en-US
Precedence: bulk


On 3/23/22 8:53 AM, Petr Mladek wrote:
> On Sat 2022-03-19 18:51:43, trix@redhat.com wrote:
>> From: Tom Rix <trix@redhat.com>
>>
>> Clang static analysis reports this issue
>> livepatch-shadow-fix1.c:113:2: warning: Use of
>>    memory after it is freed
>>    pr_info("%s: dummy @ %p, prevented leak @ %p\n",
>>    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>> The pointer is freed in the previous statement.
>> Reorder the pr_info to report before the free.
>>
>> Similar issue in livepatch-shadow-fix2.c
> I have added the following paragraph:
>
> <snip>
> Note that it is a false positive. pr_info() just prints the address.
> The freed memory is not accessed. Well, the static analyzer could not
> know this easily.
> </snip>
>
>> Signed-off-by: Tom Rix <trix@redhat.com>
> and pushed the patch into livepatching/livepatching.git,
> branch for-5.18/selftests-fixes.
>
> IMHO, the patch is so trivial and can be added even in this merge
> window. There is no need to create more dances around it ;-)
>
> Let me know if you disagree. I am going to send the pull request
> on Friday or Monday.

Do whatever is easier for you.  The addition to the commit log is fine.

Thanks

Tom

>
> Best Regards,
> Petr
>