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changeset 7422:2dad54c2b8ed stable-1.14

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Mp4: fixed possible pointer overflow on 32-bit platforms. On 32-bit platforms mp4->buffer_pos might overflow when a large enough (close to 4 gigabytes) atom is being skipped, resulting in incorrect memory addesses being read further in the code. In most cases this results in harmless errors being logged, though may also result in a segmentation fault if hitting unmapped pages. To address this, ngx_mp4_atom_next() now only increments mp4->buffer_pos up to mp4->buffer_end. This ensures that overflow cannot happen.
author Maxim Dounin <mdounin@mdounin.ru>
date Wed, 21 Nov 2018 20:23:16 +0300
parents 11be3c0723bd
children 931f9d2abf28
files src/http/modules/ngx_http_mp4_module.c
diffstat 1 files changed, 8 insertions(+), 1 deletions(-) [+]
line wrap: on
line diff
--- a/src/http/modules/ngx_http_mp4_module.c
+++ b/src/http/modules/ngx_http_mp4_module.c
@@ -169,7 +169,14 @@ typedef struct {
 
 
 #define ngx_mp4_atom_next(mp4, n)                                             \
-    mp4->buffer_pos += (size_t) n;                                            \
+                                                                              \
+    if (n > (size_t) (mp4->buffer_end - mp4->buffer_pos)) {                   \
+        mp4->buffer_pos = mp4->buffer_end;                                    \
+                                                                              \
+    } else {                                                                  \
+        mp4->buffer_pos += (size_t) n;                                        \
+    }                                                                         \
+                                                                              \
     mp4->offset += n