From ac5a568e6dff8162a2e982f3571b925f1b207e2c Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Sat, 21 Nov 2020 14:51:25 +0100 Subject: [PATCH] =?UTF-8?q?avformat/utils:=20Change=20compute=5Fchapters?= =?UTF-8?q?=5Fend()=20from=20O(n=C2=B2)=20to=20O(n=20log=20n)?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Fixes: Timeout (49sec -> 9sec) Fixes: 27427/clusterfuzz-testcase-minimized-ffmpeg_dem_FFMETADATA_fuzzer-5140589838073856 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer --- libavformat/utils.c | 46 +++++++++++++++++++++++++++++++++------------ 1 file changed, 34 insertions(+), 12 deletions(-) diff --git a/libavformat/utils.c b/libavformat/utils.c index f63ff3074a..3ba4ae4123 100644 --- a/libavformat/utils.c +++ b/libavformat/utils.c @@ -3193,31 +3193,51 @@ enum AVCodecID av_codec_get_id(const AVCodecTag *const *tags, unsigned int tag) return AV_CODEC_ID_NONE; } -static void compute_chapters_end(AVFormatContext *s) +static int chapter_start_cmp(const void *p1, const void *p2) { - unsigned int i, j; + AVChapter *ch1 = *(AVChapter**)p1; + AVChapter *ch2 = *(AVChapter**)p2; + int delta = av_compare_ts(ch1->start, ch1->time_base, ch2->start, ch2->time_base); + if (delta) + return delta; + return (ch1 > ch2) - (ch1 < ch2); +} + +static int compute_chapters_end(AVFormatContext *s) +{ + unsigned int i; int64_t max_time = 0; + AVChapter **timetable = av_malloc(s->nb_chapters * sizeof(*timetable)); + + if (!timetable) + return AVERROR(ENOMEM); if (s->duration > 0 && s->start_time < INT64_MAX - s->duration) max_time = s->duration + ((s->start_time == AV_NOPTS_VALUE) ? 0 : s->start_time); for (i = 0; i < s->nb_chapters; i++) - if (s->chapters[i]->end == AV_NOPTS_VALUE) { - AVChapter *ch = s->chapters[i]; - int64_t end = max_time ? av_rescale_q(max_time, AV_TIME_BASE_Q, - ch->time_base) - : INT64_MAX; + timetable[i] = s->chapters[i]; + qsort(timetable, s->nb_chapters, sizeof(*timetable), chapter_start_cmp); - for (j = 0; j < s->nb_chapters; j++) { - AVChapter *ch1 = s->chapters[j]; + for (i = 0; i < s->nb_chapters; i++) + if (timetable[i]->end == AV_NOPTS_VALUE) { + AVChapter *ch = timetable[i]; + int64_t end = max_time ? av_rescale_q(max_time, AV_TIME_BASE_Q, + ch->time_base) + : INT64_MAX; + + if (i + 1 < s->nb_chapters) { + AVChapter *ch1 = timetable[i + 1]; int64_t next_start = av_rescale_q(ch1->start, ch1->time_base, - ch->time_base); - if (j != i && next_start > ch->start && next_start < end) + ch->time_base); + if (next_start > ch->start && next_start < end) end = next_start; } ch->end = (end == INT64_MAX || end < ch->start) ? ch->start : end; } + av_free(timetable); + return 0; } static int get_std_framerate(int i) @@ -4073,7 +4093,9 @@ FF_ENABLE_DEPRECATION_WARNINGS } } - compute_chapters_end(ic); + ret = compute_chapters_end(ic); + if (ret < 0) + goto find_stream_info_err; /* update the stream parameters from the internal codec contexts */ for (i = 0; i < ic->nb_streams; i++) {