From f5708e66c7187c2489a7d0b39918f6d0fe4c6645 Mon Sep 17 00:00:00 2001 From: Maxim Dounin Date: Wed, 21 Nov 2018 20:23:16 +0300 Subject: [PATCH] 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. --- src/http/modules/ngx_http_mp4_module.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/src/http/modules/ngx_http_mp4_module.c b/src/http/modules/ngx_http_mp4_module.c index 2a6fafa04..618bf787b 100644 --- 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