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[83.52.55.163]) by smtp.gmail.com with ESMTPSA id y1sm7785197wmq.43.2021.08.15.07.34.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 15 Aug 2021 07:34:17 -0700 (PDT) Subject: Re: [PATCH for-6.2 0/4] Zero sockaddr_in when initializing it To: Eric Blake , Peter Maydell References: <20210813150506.7768-1-peter.maydell@linaro.org> <20210813183015.qlfqrshmplxseued@redhat.com> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Message-ID: <613eaeab-337f-a5aa-91cb-029d38d694f3@redhat.com> Date: Sun, 15 Aug 2021 16:34:16 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210813183015.qlfqrshmplxseued@redhat.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=philmd@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=philmd@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -55 X-Spam_score: -5.6 X-Spam_bar: ----- X-Spam_report: (-5.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.699, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-2.147, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jason Wang , =?UTF-8?Q?Alex_Benn=c3=a9e?= , qemu-devel@nongnu.org, Corey Minyard Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 8/13/21 8:30 PM, Eric Blake wrote: > On Fri, Aug 13, 2021 at 04:05:02PM +0100, Peter Maydell wrote: >> The POSIX spec for sockaddr_in says that implementations are allowed >> to have implementation-dependent extensions controlled by extra >> fields in the struct, and that the way to ensure these are not >> accidentally activated is to zero out the whole data structure. >> We have several places in our codebase where we don't zero-init >> sockaddr_in structs and so (at least in theory) might run into this. >> Coverity spotted the ones in the net code (CID 1005338); the >> others in this series I found by looking at all uses of sockaddr_in. >> (The gdbstub patch changes also a sockaddr_un use, for symmetry.) >> >> Thanks to Eric for the analysis of what the spec says and why >> Coverity is correct here. > > FWIW, the POSIX wording is interesting - it requires portable > applications to zero out sockaddr_in6 (and even states that memset() > is not yet a portable way to do that on exotic hardware, although a > future version of POSIX may add a zero-bit constraint on > implementations; in practice we only use qemu on hardware where > memset() to zero properly sets pointers to NULL and floating points to > 0.0). So this checkpatch.pl error (inherited from Linux) is against POSIX? 2028 # check for static initialisers. 2029 if ($line =~ /\bstatic\s.*=\s*(0|NULL|false)\s*;/) { 2030 ERROR("do not initialise statics to 0 or NULL\n" . 2031 $herecurr); 2032 } [...]