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Tue, 7 Jul 2020 05:48:13 +0000 (UTC) Subject: Re: [PATCH v2] util/qemu-option: Document the get_opt_value() function To: Markus Armbruster , Richard Henderson References: <20200629070858.19850-1-philmd@redhat.com> <1dec6cd5-42f8-8e9f-cc87-108e46a926cc@linaro.org> <87r1tnanuq.fsf@dusky.pond.sub.org> From: Thomas Huth Openpgp: preference=signencrypt Message-ID: Date: Tue, 7 Jul 2020 07:48:11 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <87r1tnanuq.fsf@dusky.pond.sub.org> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=thuth@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=205.139.110.120; envelope-from=thuth@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/06 23:10:26 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -40 X-Spam_score: -4.1 X-Spam_bar: ---- X-Spam_report: (-4.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN 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: Damien Hedde , Kevin Wolf , =?UTF-8?Q?Daniel_P_=2e_Berrang=c3=a9?= , qemu-devel@nongnu.org, =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 07/07/2020 07.35, Markus Armbruster wrote: > Richard Henderson writes: > >> On 6/29/20 12:08 AM, Philippe Mathieu-Daudé wrote: >>> Coverity noticed commit 950c4e6c94 introduced a dereference before >>> null check in get_opt_value (CID1391003): >>> >>> In get_opt_value: All paths that lead to this null pointer >>> comparison already dereference the pointer earlier (CWE-476) >>> >>> We fixed this in commit 6e3ad3f0e31, but relaxed the check in commit >>> 0c2f6e7ee99 because "No callers of get_opt_value() pass in a NULL >>> for the 'value' parameter". >>> >>> Since this function is publicly exposed, it risks new users to do >>> the same error again. Avoid that documenting the 'value' argument >>> must not be NULL. >> >> I think we should also add some use of __attribute__((nonnull(...))) to enforce >> this within the compiler. >> >> I recently did this without a qemu/compiler.h QEMU_FOO wrapper within >> target/arm. But the nonnull option has optional arguments, so it might be >> difficult to wrap in macros. > > Do we support building with a compuler that lacks this attribute? It seems to be available in GCC 4.0 already: https://gcc.gnu.org/onlinedocs/gcc-4.0.0/gcc/Function-Attributes.html ... so the answer to your question is certainly "no". All supported compilers should have this attribute. Thomas