[FFmpeg-devel] [PATCH v2 2/2] avformat/mov: re-allow zero sample sizes if that is not the default

[Marton Balint]

Patch 03d81a044ad587ea83567f75dc36bc3d64278199 disallowed zero sample sizes,
but there are some files in the wild which have zero sized samples (e.g.
no audio in some part of a live recording).

Fix this by simply ignoring a trun box with zero sized samples. This approach
fixes the original timeout issue from fuzzed files differently.

Signed-off-by: Marton Balint <cus at passwd.hu>
---
 libavformat/mov.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/libavformat/mov.c b/libavformat/mov.c
index 935b2f8d9f..63e0b614df 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -5121,6 +5121,11 @@ static int mov_read_trun(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     if (flags & MOV_TRUN_DATA_OFFSET)        data_offset        = avio_rb32(pb);
     if (flags & MOV_TRUN_FIRST_SAMPLE_FLAGS) first_sample_flags = avio_rb32(pb);
 
+    if (entries && !frag->size && !(flags & MOV_TRUN_SAMPLE_SIZE)) {
+        av_log(c->fc, AV_LOG_WARNING, "Ignoring trun box with zero sized samples\n");
+        entries = 0;
+    }
+
     frag_stream_info = get_current_frag_stream_info(&c->frag_index);
     if (frag_stream_info) {
         if (frag_stream_info->next_trun_dts != AV_NOPTS_VALUE) {
@@ -5293,8 +5298,6 @@ static int mov_read_trun(MOVContext *c, AVIOContext *pb, MOVAtom atom)
         distance++;
         if (av_sat_add64(dts, sample_duration) != dts + (uint64_t)sample_duration)
             return AVERROR_INVALIDDATA;
-        if (!sample_size)
-            return AVERROR_INVALIDDATA;
         dts += sample_duration;
         offset += sample_size;
         sc->data_size += sample_size;
-- 
2.35.3