* [FFmpeg-devel] [PR] avformat/dashdec: check value valid after read value from mpd xml (PR #21568)
@ 2026-01-24 7:50 stevenliu via ffmpeg-devel
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From: stevenliu via ffmpeg-devel @ 2026-01-24 7:50 UTC (permalink / raw)
To: ffmpeg-devel; +Cc: stevenliu
PR #21568 opened by stevenliu
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21568
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21568.patch
before this commit ffmpeg get Heap Buffer Overflow in DASH Demuxer
via Negative Start Number.
Check the value from mpd xml, set the value to 0 if get negative value.
Fixes: heap buffer overflow
Found-by: Zhenpeng (Leo) Lin from depthfirst
Signed-off-by: Steven Liu <lq@chinaffmpeg.org>
>From e0f26e0019ea8b4f17de56eddac943b5e2c7093f Mon Sep 17 00:00:00 2001
From: Steven Liu <lq@chinaffmpeg.org>
Date: Sat, 24 Jan 2026 15:22:15 +0800
Subject: [PATCH] avformat/dashdec: check value valid after read value from mpd
xml
before this commit ffmpeg get Heap Buffer Overflow in DASH Demuxer
via Negative Start Number.
Check the value from mpd xml, set the value to 0 if get negative value.
Fixes: heap buffer overflow
Found-by: Zhenpeng (Leo) Lin from depthfirst
Signed-off-by: Steven Liu <lq@chinaffmpeg.org>
---
libavformat/dashdec.c | 49 ++++++++++++++++++++++++++++++++++++-------
1 file changed, 42 insertions(+), 7 deletions(-)
diff --git a/libavformat/dashdec.c b/libavformat/dashdec.c
index 500d8ca518..a41f4b7c5f 100644
--- a/libavformat/dashdec.c
+++ b/libavformat/dashdec.c
@@ -957,25 +957,45 @@ static int parse_manifest_representation(AVFormatContext *s, const char *url,
}
val = get_val_from_nodes_tab(fragment_templates_tab, 4, "presentationTimeOffset");
if (val) {
- rep->presentation_timeoffset = (int64_t) strtoll(val, NULL, 10);
+ int64_t presentation_timeoffset = (int64_t) strtoll(val, NULL, 10);
+ if (presentation_timeoffset < 0) {
+ av_log(s, AV_LOG_WARNING, "The presentationTimeOffset value invalid, autochanged to 0.\n");
+ presentation_timeoffset = 0;
+ }
+ rep->presentation_timeoffset = presentation_timeoffset;
av_log(s, AV_LOG_TRACE, "rep->presentation_timeoffset = [%"PRId64"]\n", rep->presentation_timeoffset);
xmlFree(val);
}
val = get_val_from_nodes_tab(fragment_templates_tab, 4, "duration");
if (val) {
- rep->fragment_duration = (int64_t) strtoll(val, NULL, 10);
+ int64_t fragment_duration = (int64_t) strtoll(val, NULL, 10);
+ if (fragment_duration < 0) {
+ av_log(s, AV_LOG_WARNING, "The duration value invalid, autochanged to 0.\n");
+ fragment_duration = 0;
+ }
+ rep->fragment_duration = fragment_duration;
av_log(s, AV_LOG_TRACE, "rep->fragment_duration = [%"PRId64"]\n", rep->fragment_duration);
xmlFree(val);
}
val = get_val_from_nodes_tab(fragment_templates_tab, 4, "timescale");
if (val) {
- rep->fragment_timescale = (int64_t) strtoll(val, NULL, 10);
+ int64_t fragment_timescale = (int64_t) strtoll(val, NULL, 10);
+ if (fragment_timescale < 0) {
+ av_log(s, AV_LOG_WARNING, "The timescale value invalid, autochanged to 0.\n");
+ fragment_timescale = 0;
+ }
+ rep->fragment_timescale = fragment_timescale;
av_log(s, AV_LOG_TRACE, "rep->fragment_timescale = [%"PRId64"]\n", rep->fragment_timescale);
xmlFree(val);
}
val = get_val_from_nodes_tab(fragment_templates_tab, 4, "startNumber");
if (val) {
- rep->start_number = rep->first_seq_no = (int64_t) strtoll(val, NULL, 10);
+ int64_t start_number = (int64_t) strtoll(val, NULL, 10);
+ if (start_number < 0) {
+ av_log(s, AV_LOG_WARNING, "The startNumber value invalid, autochanged to 0.\n");
+ start_number = 0;
+ }
+ rep->start_number = rep->first_seq_no = start_number;
av_log(s, AV_LOG_TRACE, "rep->first_seq_no = [%"PRId64"]\n", rep->first_seq_no);
xmlFree(val);
}
@@ -1037,19 +1057,34 @@ static int parse_manifest_representation(AVFormatContext *s, const char *url,
val = get_val_from_nodes_tab(segmentlists_tab, 3, "duration");
if (val) {
- rep->fragment_duration = (int64_t) strtoll(val, NULL, 10);
+ int64_t fragment_duration = (int64_t) strtoll(val, NULL, 10);
+ if (fragment_duration < 0) {
+ av_log(s, AV_LOG_WARNING, "The duration value invalid, autochanged to 0.\n");
+ fragment_duration = 0;
+ }
+ rep->fragment_duration = fragment_duration;
av_log(s, AV_LOG_TRACE, "rep->fragment_duration = [%"PRId64"]\n", rep->fragment_duration);
xmlFree(val);
}
val = get_val_from_nodes_tab(segmentlists_tab, 3, "timescale");
if (val) {
- rep->fragment_timescale = (int64_t) strtoll(val, NULL, 10);
+ int64_t fragment_timescale = (int64_t) strtoll(val, NULL, 10);
+ if (fragment_timescale < 0) {
+ av_log(s, AV_LOG_WARNING, "The timescale value invalid, autochanged to 0.\n");
+ fragment_timescale = 0;
+ }
+ rep->fragment_timescale = fragment_timescale;
av_log(s, AV_LOG_TRACE, "rep->fragment_timescale = [%"PRId64"]\n", rep->fragment_timescale);
xmlFree(val);
}
val = get_val_from_nodes_tab(segmentlists_tab, 3, "startNumber");
if (val) {
- rep->start_number = rep->first_seq_no = (int64_t) strtoll(val, NULL, 10);
+ int64_t start_number = (int64_t) strtoll(val, NULL, 10);
+ if (start_number < 0) {
+ av_log(s, AV_LOG_WARNING, "The startNumber value invalid, autochanged to 0.\n");
+ start_number = 0;
+ }
+ rep->start_number = rep->first_seq_no = start_number;
av_log(s, AV_LOG_TRACE, "rep->first_seq_no = [%"PRId64"]\n", rep->first_seq_no);
xmlFree(val);
}
--
2.52.0
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2026-01-24 7:50 [FFmpeg-devel] [PR] avformat/dashdec: check value valid after read value from mpd xml (PR #21568) stevenliu via ffmpeg-devel
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