[FFmpeg-devel] [PATCH v2] libavcodec/cbs_av1: Add size check before parse obu

[Wenbin Chen]

cbs_av1_write_unit() check pbc size after parsing obu frame, and return
AVERROR(ENOSPC) if pbc is small. pbc will be reallocated and this obu
frame will be parsed again, but this may cause error because
CodedBitstreamAV1Context has already been updated, for example
ref_order_hint is updated and will not match the same obu frame. Now size
check is added before parsing obu frame to avoid this error.

Signed-off-by: Wenbin Chen <wenbin.chen at intel.com>
---
 libavcodec/cbs_av1.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/libavcodec/cbs_av1.c b/libavcodec/cbs_av1.c
index 1229480567..29e7bc16df 100644
--- a/libavcodec/cbs_av1.c
+++ b/libavcodec/cbs_av1.c
@@ -1075,6 +1075,9 @@ static int cbs_av1_write_obu(CodedBitstreamContext *ctx,
         put_bits32(pbc, 0);
     }
 
+    if (8 * (unit->data_size + obu->obu_size) > put_bits_left(pbc))
+        return AVERROR(ENOSPC);
+
     td = NULL;
     start_pos = put_bits_count(pbc);
 
@@ -1196,9 +1199,6 @@ static int cbs_av1_write_obu(CodedBitstreamContext *ctx,
     flush_put_bits(pbc);
     av_assert0(data_pos <= start_pos);
 
-    if (8 * obu->obu_size > put_bits_left(pbc))
-        return AVERROR(ENOSPC);
-
     if (obu->obu_size > 0) {
         memmove(pbc->buf + data_pos,
                 pbc->buf + start_pos, header_size);
-- 
2.32.0