From patchwork Tue Apr 16 14:48:31 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Niedermayer X-Patchwork-Id: 12767 Return-Path: X-Original-To: patchwork@ffaux-bg.ffmpeg.org Delivered-To: patchwork@ffaux-bg.ffmpeg.org Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100]) by ffaux.localdomain (Postfix) with ESMTP id 6D2DF44903C for ; Tue, 16 Apr 2019 17:51:19 +0300 (EEST) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 5ADB568A551; Tue, 16 Apr 2019 17:51:19 +0300 (EEST) X-Original-To: ffmpeg-devel@ffmpeg.org Delivered-To: ffmpeg-devel@ffmpeg.org Received: from vie01a-dmta-pe07-1.mx.upcmail.net (vie01a-dmta-pe07-1.mx.upcmail.net [84.116.36.17]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id D594C68A3AF for ; Tue, 16 Apr 2019 17:51:10 +0300 (EEST) Received: from [172.31.216.235] (helo=vie01a-pemc-psmtp-pe12.mail.upcmail.net) by vie01a-dmta-pe07.mx.upcmail.net with esmtp (Exim 4.91) (envelope-from ) id 1hGPQU-0003x5-0w for ffmpeg-devel@ffmpeg.org; Tue, 16 Apr 2019 16:51:10 +0200 Received: from localhost ([213.47.41.20]) by vie01a-pemc-psmtp-pe12.mail.upcmail.net with ESMTP id GPPVhJUKP5D5NGPPVhUVQ8; Tue, 16 Apr 2019 16:50:10 +0200 X-Env-Mailfrom: michael@niedermayer.cc X-Env-Rcptto: ffmpeg-devel@ffmpeg.org X-SourceIP: 213.47.41.20 X-CNFS-Analysis: v=2.3 cv=bu8y+3Si c=1 sm=1 tr=0 a=I1eytVlZLDX1BM2VTtTtSw==:117 a=I1eytVlZLDX1BM2VTtTtSw==:17 a=MKtGQD3n3ToA:10 a=1oJP67jkp3AA:10 a=GEAsPZ9sns4A:10 a=ZZnuYtJkoWoA:10 a=BWy5e9jQ0DNfsth7XSkA:9 From: Michael Niedermayer To: FFmpeg development discussions and patches Date: Tue, 16 Apr 2019 16:48:31 +0200 Message-Id: <20190416144834.20300-1-michael@niedermayer.cc> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 X-CMAE-Envelope: MS4wfEbuXVZZG5UKrQA052BM1po8jLKAGLaYITakut8ovG0qF+xnRTJ22w3O0cHtvooRJH9JH8WtLsVdYn5aD0FYeJwdwLzYU/iI4ExL1eJs80wQPpTTCbnX suuNxDwTDZffXRB2yVRlVbiymbdLklzLSnMzG53eyW8m19ZbHPd0Yy51 Subject: [FFmpeg-devel] [PATCH 1/4] avutil/avstring: Fix bug and undefined behavior in av_strncasecmp() X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" The function in case of n=0 would read more bytes than 0. The end pointer could be beyond the allocated space, which is undefined. Signed-off-by: Michael Niedermayer --- libavutil/avstring.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/libavutil/avstring.c b/libavutil/avstring.c index f03dd25141..4c068f5bc5 100644 --- a/libavutil/avstring.c +++ b/libavutil/avstring.c @@ -222,12 +222,13 @@ int av_strcasecmp(const char *a, const char *b) int av_strncasecmp(const char *a, const char *b, size_t n) { - const char *end = a + n; uint8_t c1, c2; + if (n <= 0) + return 0; do { c1 = av_tolower(*a++); c2 = av_tolower(*b++); - } while (a < end && c1 && c1 == c2); + } while (--n && c1 && c1 == c2); return c1 - c2; }