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Git pushed a commit to branch release/5.1
in repository ffmpeg.

commit ff97be6e23cd7947c5e231b2fd4cd46480e8812c
Author:     Steven Liu <[email protected]>
AuthorDate: Sun Jan 25 11:20:39 2026 +0800
Commit:     Michael Niedermayer <[email protected]>
CommitDate: Tue May 5 15:20:59 2026 +0200

    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
    (cherry picked from commit a97632827dbff20c50a331787c3af31745e49e87)
    Signed-off-by: Michael Niedermayer <[email protected]>
---
 libavformat/dashdec.c | 84 ++++++++++++++++++++++++++++-----------------------
 1 file changed, 46 insertions(+), 38 deletions(-)

diff --git a/libavformat/dashdec.c b/libavformat/dashdec.c
index b688942c04..83785cb13d 100644
--- a/libavformat/dashdec.c
+++ b/libavformat/dashdec.c
@@ -828,6 +828,43 @@ end:
 
 }
 
+#define SET_REPRESENTATION_SEQUENCE_BASE_INFO(arg, cnt) { \
+        val = get_val_from_nodes_tab((arg), (cnt), "duration"); \
+        if (val) { \
+            int64_t fragment_duration = (int64_t) strtoll(val, NULL, 10); \
+            if (fragment_duration < 0) { \
+                av_log(s, AV_LOG_WARNING, "duration 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((arg), (cnt), "timescale"); \
+        if (val) { \
+            int64_t fragment_timescale = (int64_t) strtoll(val, NULL, 10); \
+            if (fragment_timescale < 0) { \
+                av_log(s, AV_LOG_WARNING, "timescale 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((arg), (cnt), "startNumber"); \
+        if (val) { \
+            int64_t start_number = (int64_t) strtoll(val, NULL, 10); \
+            if (start_number < 0) { \
+                av_log(s, AV_LOG_WARNING, "startNumber 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); \
+        } \
+    }
+
+
 static int parse_manifest_representation(AVFormatContext *s, const char *url,
                                          xmlNodePtr node,
                                          xmlNodePtr adaptionset_node,
@@ -942,28 +979,17 @@ 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, "presentationTimeOffset 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);
-            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);
-            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);
-            av_log(s, AV_LOG_TRACE, "rep->first_seq_no = [%"PRId64"]\n", 
rep->first_seq_no);
-            xmlFree(val);
-        }
+
+        SET_REPRESENTATION_SEQUENCE_BASE_INFO(fragment_templates_tab, 4);
         if (adaptionset_supplementalproperty_node) {
             char *scheme_id_uri = 
xmlGetProp(adaptionset_supplementalproperty_node, "schemeIdUri");
             if (scheme_id_uri) {
@@ -1020,25 +1046,7 @@ static int parse_manifest_representation(AVFormatContext 
*s, const char *url,
         segmentlists_tab[1] = adaptionset_segmentlist_node;
         segmentlists_tab[2] = period_segmentlist_node;
 
-        val = get_val_from_nodes_tab(segmentlists_tab, 3, "duration");
-        if (val) {
-            rep->fragment_duration = (int64_t) strtoll(val, NULL, 10);
-            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);
-            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);
-            av_log(s, AV_LOG_TRACE, "rep->first_seq_no = [%"PRId64"]\n", 
rep->first_seq_no);
-            xmlFree(val);
-        }
-
+        SET_REPRESENTATION_SEQUENCE_BASE_INFO(segmentlists_tab, 3)
         fragmenturl_node = 
xmlFirstElementChild(representation_segmentlist_node);
         while (fragmenturl_node) {
             ret = parse_manifest_segmenturlnode(s, rep, fragmenturl_node,

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