From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <ffmpeg-devel-bounces@ffmpeg.org> Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTPS id 5BF194CADF for <ffmpegdev@gitmailbox.com>; Fri, 11 Apr 2025 09:00:51 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 0ED6668C17A; Fri, 11 Apr 2025 12:00:47 +0300 (EEST) Received: from out162-62-57-210.mail.qq.com (out162-62-57-210.mail.qq.com [162.62.57.210]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id C34FF687A92 for <ffmpeg-devel@ffmpeg.org>; Fri, 11 Apr 2025 12:00:39 +0300 (EEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=foxmail.com; s=s201512; t=1744362035; bh=5ShjT1VcPGcKBBIN325neLLuTtNLoJX7Wam+gaNxXpU=; h=From:Subject:Date:References:To:In-Reply-To; b=pit9PQ+SGy7TBFoz8bh7UPdOYXUO4oVzymHd7ga25ZGUowpHTI/yw5p2rbhE2vB6G pi0rR7QawMEzTID9rhXgTV0XYtv0NqD1nN/diJhh+EmAnrSBYQzsP6Zava0qycw1xG gXxPL2VsVF6vjoCmdIBKil+5TEfEMDg694hOVht4= Received: from smtpclient.apple ([119.147.10.242]) by newxmesmtplogicsvrsza36-0.qq.com (NewEsmtp) with SMTP id 21B6C13; Fri, 11 Apr 2025 17:00:33 +0800 X-QQ-mid: xmsmtpt1744362033tkc7s4run Message-ID: <tencent_2E0DD0B5E6CFA7CCAAA4532B9C428B87A606@qq.com> X-QQ-XMAILINFO: NvH2zBBgt3uTTIYJ2WzfRJRpIPDvQhAgoYkziBIoEtW/PjiCpqaUsT4iG9zYRu U3kmueA19rJqFAr35i0Fu8iZC/YqROZzFKiqu628Fe3eRms630B6Mh9Bmz59PnnvuMA/ZoNMsAHm 8hPkgorTC9FUxjqCqwIJw1KLofxzd1m2lBECLj3liocx28+kAsltgnK1TMHrSL2fR1k3V9W3rqiB BUw+2f5plFxhiIy3sO0LLB46ARNSyKGsYL8hqal9Ovw+xp2YK/tcog3PbZvpM1KSpIyRY29cI792 iDNdYD/w23UdqY+uW2jzU90wuZLugj/KnyOOTTAKVGGrrIEKEhx22xFrVrvLGrnff4JoNaN80wUn zFnXicKIQld1pEQKwG/86BIv/zjtSfDjl7iGMaZB8Mu5wyENrHknPFpu2J4PgOqA7BriB68BISCF /fJxVZ2vlqIsASBgmbssN0PN+bZQAYTOwIpOwiPdhWrfuel605DMgaITyjD2uKlQYoQCr7cTHh2y WSyhHWvSU7lJ03pQTZ+KqT39pWkCUyVcO/D31K0sAxNofTAJu5A91vvDlCeXxPfuGdWk0q1hgw2V FOFkWxgiYOblWXUryN6wtQcV/Gt86FKUTLcZ43y2NL26u6ZtP48dbcZya0UiuSa0wwBI7s+lXLBT ZkXj9V2VsFjyqpMsux67Jbc6/+X7uR8HKOmoxOhxWH2bixh3/wuRkoCuOSFPgKbYDQDf4NY2Yjok H8wOvzYQvi1mrNLRMam5/vxmSvFYPVKlK1APtzt6rBp2HpVat3DQj9g4VJqVK7yHnKA0bbmKxHkz 9fc15eGq9tD3/j2dTsZPyQJ/+HexuB5dMmb5sdutKIqXjbZequpE2bvbEbPhtAsjbpbj1uEtlITm B+ZbuyuB6cO9199YcU15RjAkf4rMvrUSVQf5c2FI5+BYoL6kfQJ5D8ydCILKHMPlOMwhCcQLf9PG GpK9klIfb0HOR0g5MxKTDOj8Qx0Lo2inL7lCh9XLHkX2yk5mZpaw== X-QQ-XMRINFO: MSVp+SPm3vtS1Vd6Y4Mggwc= From: Zhao Zhili <quinkblack-at-foxmail.com@ffmpeg.org> Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3818.100.11.1.3\)) Date: Fri, 11 Apr 2025 17:00:23 +0800 References: <tencent_079C0CE00E5AB635FB818234013E7F56A909@qq.com> <Z_jUgQrjVSXkDfvN@phare.normalesup.org> To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org> In-Reply-To: <Z_jUgQrjVSXkDfvN@phare.normalesup.org> X-OQ-MSGID: <F84458AC-694A-4962-8F4E-370F170C2C75@foxmail.com> X-Mailer: Apple Mail (2.3818.100.11.1.3) Subject: Re: [FFmpeg-devel] [PATCH 00/22] Deprecate av_uninit X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches <ffmpeg-devel.ffmpeg.org> List-Unsubscribe: <https://ffmpeg.org/mailman/options/ffmpeg-devel>, <mailto:ffmpeg-devel-request@ffmpeg.org?subject=unsubscribe> List-Archive: <https://ffmpeg.org/pipermail/ffmpeg-devel> List-Post: <mailto:ffmpeg-devel@ffmpeg.org> List-Help: <mailto:ffmpeg-devel-request@ffmpeg.org?subject=help> List-Subscribe: <https://ffmpeg.org/mailman/listinfo/ffmpeg-devel>, <mailto:ffmpeg-devel-request@ffmpeg.org?subject=subscribe> Reply-To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org> Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" <ffmpeg-devel-bounces@ffmpeg.org> Archived-At: <https://master.gitmailbox.com/ffmpegdev/tencent_2E0DD0B5E6CFA7CCAAA4532B9C428B87A606@qq.com/> List-Archive: <https://master.gitmailbox.com/ffmpegdev/> List-Post: <mailto:ffmpegdev@gitmailbox.com> > On Apr 11, 2025, at 16:36, Nicolas George <george@nsup.org> wrote: > > Zhao Zhili (HE12025-04-11): >> From: Zhao Zhili <zhilizhao@tencent.com> >> >> The macro is meant to suppress false uninitialized warnings. However, >> sometimes these 'false uninitialized warnings' are really undefined >> behavior, and leading to real issue like crash, e.g., ab792634197e. >> >> For false uninitialized warnings, it can be silenced by initialization, >> and compiler can easily optimize away unnecessary initializations. >> >> av_uninit shouldn't be used in any case. > > NAK, you are hiding the UBs, not fixing the bugs. > > If the author of the code put av_uninit, that means they believe the > value will always have been initialized by the part of the code > responsible for it. If that is not true, then it is a bug that can lead > to an exploitable security issue or a silent data corruption. > > With your changes, nothing proves that the = 0 you put there is the > right value, the bug is still there: the code expects the value to be > correctly set, but instead there is an arbitrary 0. > > At least, with av_uninit, valgrind and fuzzing can find the bugs. With UB, the compiler can remove branch check and assign some random value to it, which cannot be detected by valgrind. For ab792634197e, the UB is there for decades and never detected by valgrind, and the warning is silenced by av_uninit. > > Regards, > > -- > Nicolas George > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe". _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".