From 88955b1044ef38315b77ad1a509d63631a790a0f Mon Sep 17 00:00:00 2001
From: Roman Arutyunyan <arut@nginx.com>
Date: Mon, 12 Aug 2024 18:20:45 +0400
Subject: [PATCH] Mp4: rejecting unordered chunks in stsc atom.

Unordered chunks could result in trak->end_chunk smaller than trak->start_chunk
in ngx_http_mp4_crop_stsc_data().  Later in ngx_http_mp4_update_stco_atom()
this caused buffer overread while trying to calculate trak->end_offset.
---
 src/http/modules/ngx_http_mp4_module.c | 7 +++++++
 1 file changed, 7 insertions(+)

--- a/src/http/modules/ngx_http_mp4_module.c
+++ b/src/http/modules/ngx_http_mp4_module.c
@@ -2972,6 +2972,13 @@ ngx_http_mp4_crop_stsc_data(ngx_http_mp4
 
         next_chunk = ngx_mp4_get_32value(entry->chunk);
 
+        if (next_chunk < chunk) {
+            ngx_log_error(NGX_LOG_ERR, mp4->file.log, 0,
+                          "unordered mp4 stsc chunks in \"%s\"",
+                          mp4->file.name.data);
+            return NGX_ERROR;
+        }
+
         ngx_log_debug5(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0,
                        "sample:%uD, chunk:%uD, chunks:%uD, "
                        "samples:%uD, id:%uD",
