From patchwork Sun Jan 15 09:59:33 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anton Khirnov X-Patchwork-Id: 40007 Delivered-To: ffmpegpatchwork2@gmail.com Received: by 2002:a05:6a20:1d43:b0:b8:6755:f97e with SMTP id cs3csp254798pzb; Sun, 15 Jan 2023 02:00:07 -0800 (PST) X-Google-Smtp-Source: AMrXdXssYeDzNq0uZBrkbHzvoEiZ3fhzWTMb4YWQMYATv3oDmopCKM2ux9zhKaO4AmpAYPXOlwEK X-Received: by 2002:a17:907:c081:b0:84d:207d:c00e with SMTP id st1-20020a170907c08100b0084d207dc00emr31481835ejc.46.1673776807481; Sun, 15 Jan 2023 02:00:07 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1673776807; cv=none; d=google.com; s=arc-20160816; b=crSY4djb4MWrQs+I1sco9RrBAnGRJ+xO/2JejV/aBXQmifulFe69jiFeP1SAbIIRPG M+6OKHbWi7CEeSme6jWTflOAInvStfpbKLoT4LzBUENwkK5D0azMqmanQ3pJmMT6csDg V3Wcxd0XU8111kr55+YpMxt16RzIPaZ5vT9ttd0ti10l2PifdODfCKyNOM96LgmkBn5y nYVcJC52zzoxc21DyxCsxeNlVbi5A0Sz8IC0xrpwEf8JQ9q3K/a5HppD2Ih6cgeRiWGL tQyYhRogjn6tUAG4ybL24PbvTDOi+2QFPt7vCKcGd0BunVwLpbp8CvW88rOKuh2JzMQR p8RA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=sender:errors-to:content-transfer-encoding:reply-to:list-subscribe :list-help:list-post:list-archive:list-unsubscribe:list-id :precedence:subject:mime-version:message-id:date:to:from :delivered-to; bh=MOdoDQxU77p0btH0MLHmBRKuHUIhTJcJfhWBNI26BNc=; b=KM9c8iTBVkvGe00Si3Q3du8m0V13xGU4CuTnwMe5lhI9YNxwMzBPe0el8hzYMH7wWh aU/sIpDYMKO6xPQa9jAFLn+uSwHc5Bl05ttqTzXQ0MyBCucFjfHno5/JSPzvhCdaDCuw uxIngN8FxxxokXZB4dPbALG5+02H+tHWerW8bKLrsL6sokKqvueCMCb8Ez1Qs1nM6wyi 95bAQVrY0WHpDpUBuni15pvKtts5NPD/HFA+KpaYBsV3WWk5dWYag6+odUegYsYHBtYo Nn9nhdj0Su6ZBCCl8GMkbIudhxL8gVegqjOROLXbCGSF5a90UtDKdConDO6kSqpnr15s KlhQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of ffmpeg-devel-bounces@ffmpeg.org designates 79.124.17.100 as permitted sender) smtp.mailfrom=ffmpeg-devel-bounces@ffmpeg.org Return-Path: Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org. [79.124.17.100]) by mx.google.com with ESMTP id a21-20020a1709066d5500b0086ce51bce8bsi3993758ejt.899.2023.01.15.02.00.06; Sun, 15 Jan 2023 02:00:07 -0800 (PST) Received-SPF: pass (google.com: domain of ffmpeg-devel-bounces@ffmpeg.org designates 79.124.17.100 as permitted sender) client-ip=79.124.17.100; Authentication-Results: mx.google.com; spf=pass (google.com: domain of ffmpeg-devel-bounces@ffmpeg.org designates 79.124.17.100 as permitted sender) smtp.mailfrom=ffmpeg-devel-bounces@ffmpeg.org Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id F398E68BC1A; Sun, 15 Jan 2023 11:59:55 +0200 (EET) X-Original-To: ffmpeg-devel@ffmpeg.org Delivered-To: ffmpeg-devel@ffmpeg.org Received: from mail0.khirnov.net (red.khirnov.net [176.97.15.12]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 99D3D68BBEA for ; Sun, 15 Jan 2023 11:59:47 +0200 (EET) Received: from localhost (localhost [IPv6:::1]) by mail0.khirnov.net (Postfix) with ESMTP id 291012400F5 for ; Sun, 15 Jan 2023 10:59:47 +0100 (CET) Received: from mail0.khirnov.net ([IPv6:::1]) by localhost (mail0.khirnov.net [IPv6:::1]) (amavisd-new, port 10024) with ESMTP id kqgyQdnVQ4pA for ; Sun, 15 Jan 2023 10:59:45 +0100 (CET) Received: from libav.khirnov.net (libav.khirnov.net [IPv6:2a00:c500:561:201::7]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "libav.khirnov.net", Issuer "smtp.khirnov.net SMTP CA" (verified OK)) by mail0.khirnov.net (Postfix) with ESMTPS id 9FC83240499 for ; Sun, 15 Jan 2023 10:59:45 +0100 (CET) Received: from libav.khirnov.net (libav.khirnov.net [IPv6:::1]) by libav.khirnov.net (Postfix) with ESMTP id 21AF33A02AF for ; Sun, 15 Jan 2023 10:59:37 +0100 (CET) From: Anton Khirnov To: ffmpeg-devel@ffmpeg.org Date: Sun, 15 Jan 2023 10:59:33 +0100 Message-Id: <20230115095934.9065-1-anton@khirnov.net> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 Subject: [FFmpeg-devel] [PATCH 1/2] lavc/bitstream: avoid UB in bits_{read, peek}_signed(0) X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 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" X-TUID: juGvRNRK7Dvj bits_*_signed(0) will currently invoke an undefined shift by 8 * sizeof(int). Add bits_*_signed_nz() that only works for n>0, analogous to bits_read_nz(). Add an explicit check for n=0 in bits_*_signed(). Found-by: James Almer --- libavcodec/bitstream.h | 4 ++++ libavcodec/bitstream_template.h | 36 +++++++++++++++++++++++++++++++-- libavcodec/get_bits.h | 2 +- 3 files changed, 39 insertions(+), 3 deletions(-) diff --git a/libavcodec/bitstream.h b/libavcodec/bitstream.h index ef7d8d55c2..b60f0c296d 100644 --- a/libavcodec/bitstream.h +++ b/libavcodec/bitstream.h @@ -89,9 +89,11 @@ # define bits_read_63 bits_read_63_le # define bits_read_64 bits_read_64_le # define bits_read_signed bits_read_signed_le +# define bits_read_signed_nz bits_read_signed_nz_le # define bits_peek_nz bits_peek_nz_le # define bits_peek bits_peek_le # define bits_peek_signed bits_peek_signed_le +# define bits_peek_signed_nz bits_peek_signed_nz_le # define bits_skip bits_skip_le # define bits_seek bits_seek_le # define bits_align bits_align_le @@ -115,9 +117,11 @@ # define bits_read_63 bits_read_63_be # define bits_read_64 bits_read_64_be # define bits_read_signed bits_read_signed_be +# define bits_read_signed_nz bits_read_signed_nz_be # define bits_peek_nz bits_peek_nz_be # define bits_peek bits_peek_be # define bits_peek_signed bits_peek_signed_be +# define bits_peek_signed_nz bits_peek_signed_nz_be # define bits_skip bits_skip_be # define bits_seek bits_seek_be # define bits_align bits_align_be diff --git a/libavcodec/bitstream_template.h b/libavcodec/bitstream_template.h index f2c14fc4d3..30bea84add 100644 --- a/libavcodec/bitstream_template.h +++ b/libavcodec/bitstream_template.h @@ -290,13 +290,29 @@ static inline uint64_t BS_FUNC(read_64)(BSCTX *bc, unsigned int n) return BS_FUNC(read_63)(bc, n); } +/** + * Return n bits from the buffer as a signed integer, n has to be in the 1-32 + * range. May be faster than bits_read_signed() when n is not a compile-time + * constant and is known to be non-zero; + */ +static inline int32_t BS_FUNC(read_signed_nz)(BSCTX *bc, unsigned int n) +{ + av_assert2(n > 0 && n <= 32); + return sign_extend(BS_FUNC(read_nz)(bc, n), n); +} + /** * Return n bits from the buffer as a signed integer. * n has to be in the 0-32 range. */ static inline int32_t BS_FUNC(read_signed)(BSCTX *bc, unsigned int n) { - return sign_extend(BS_FUNC(read)(bc, n), n); + av_assert2(n <= 32); + + if (!n) + return 0; + + return BS_FUNC(read_signed_nz)(bc, n); } /** @@ -327,6 +343,17 @@ static inline uint32_t BS_FUNC(peek)(BSCTX *bc, unsigned int n) return BS_FUNC(peek_nz)(bc, n); } +/** + * Return n bits from the buffer as a signed integer, do not change the buffer + * state. n has to be in the 1-32 range. May be faster than bits_peek_signed() + * when n is not a compile-time constant and is known to be non-zero; + */ +static inline int BS_FUNC(peek_signed_nz)(BSCTX *bc, unsigned int n) +{ + av_assert2(n > 0 && n <= 32); + return sign_extend(BS_FUNC(peek_nz)(bc, n), n); +} + /** * Return n bits from the buffer as a signed integer, * do not change the buffer state. @@ -334,7 +361,12 @@ static inline uint32_t BS_FUNC(peek)(BSCTX *bc, unsigned int n) */ static inline int BS_FUNC(peek_signed)(BSCTX *bc, unsigned int n) { - return sign_extend(BS_FUNC(peek)(bc, n), n); + av_assert2(n <= 32); + + if (!n) + return 0; + + return BS_FUNC(peek_signed_nz)(bc, n); } /** diff --git a/libavcodec/get_bits.h b/libavcodec/get_bits.h index 1aa327a4ac..65dc080ddb 100644 --- a/libavcodec/get_bits.h +++ b/libavcodec/get_bits.h @@ -85,7 +85,7 @@ typedef BitstreamContext GetBitContext; #define get_bits1 bits_read_bit #define get_bits64 bits_read_64 #define get_xbits bits_read_xbits -#define get_sbits bits_read_signed +#define get_sbits bits_read_signed_nz #define get_sbits_long bits_read_signed #define show_bits bits_peek #define show_bits_long bits_peek