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From: Roman Arutyunyan <arut@nginx.com>
Date: Mon, 12 Aug 2024 18:20:43 +0400
Subject: Mp4: fixed buffer underread while updating stsz atom.
While cropping an stsc atom in ngx_http_mp4_crop_stsc_data(), a 32-bit integer
overflow could happen, which could result in incorrect seeking and a very large
value stored in "samples". This resulted in a large invalid value of
trak->end_chunk_samples. This value is further used to calculate the value of
trak->end_chunk_samples_size in ngx_http_mp4_update_stsz_atom(). While doing
this, a large invalid value of trak->end_chunk_samples could result in reading
memory before stsz atom start. This could potentially result in a segfault.
Origin: upstream, https://github.com/nginx/nginx/commit/7362d01658b61184108c21278443910da68f93b4
---
src/http/modules/ngx_http_mp4_module.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/src/http/modules/ngx_http_mp4_module.c b/src/http/modules/ngx_http_mp4_module.c
index 4eff01e..460d091 100644
--- a/src/http/modules/ngx_http_mp4_module.c
+++ b/src/http/modules/ngx_http_mp4_module.c
@@ -3098,7 +3098,8 @@ static ngx_int_t
ngx_http_mp4_crop_stsc_data(ngx_http_mp4_file_t *mp4,
ngx_http_mp4_trak_t *trak, ngx_uint_t start)
{
- uint32_t start_sample, chunk, samples, id, next_chunk, n,
+ uint64_t n;
+ uint32_t start_sample, chunk, samples, id, next_chunk,
prev_samples;
ngx_buf_t *data, *buf;
ngx_uint_t entries, target_chunk, chunk_samples;
@@ -3159,7 +3160,7 @@ ngx_http_mp4_crop_stsc_data(ngx_http_mp4_file_t *mp4,
"samples:%uD, id:%uD",
start_sample, chunk, next_chunk - chunk, samples, id);
- n = (next_chunk - chunk) * samples;
+ n = (uint64_t) (next_chunk - chunk) * samples;
if (start_sample < n) {
goto found;
@@ -3181,7 +3182,7 @@ ngx_http_mp4_crop_stsc_data(ngx_http_mp4_file_t *mp4,
"sample:%uD, chunk:%uD, chunks:%uD, samples:%uD",
start_sample, chunk, next_chunk - chunk, samples);
- n = (next_chunk - chunk) * samples;
+ n = (uint64_t) (next_chunk - chunk) * samples;
if (start_sample > n) {
ngx_log_error(NGX_LOG_ERR, mp4->file.log, 0,
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