[FFmpeg-devel] [PATCH] cbs_apv: Fix memory leak on metadata parse failure

[FFmpeg-devel] [PATCH] cbs_apv: Fix memory leak on metadata parse failure

[Mark Thompson]

Buffers are allocated inside some metadata types, so we must ensure
that the object is visible to the free function before a parse failure.

Found by libFuzzer.
---
 libavcodec/cbs_apv_syntax_template.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/cbs_apv_syntax_template.c b/libavcodec/cbs_apv_syntax_template.c
index ca66349141..fc8a08ff31 100644
--- a/libavcodec/cbs_apv_syntax_template.c
+++ b/libavcodec/cbs_apv_syntax_template.c
@@ -543,11 +543,11 @@ static int FUNC(metadata)(CodedBitstreamContext *ctx, RWContext *rw,
             return AVERROR_INVALIDDATA;
         }
 
+        current->metadata_count = p + 1;
+
         CHECK(FUNC(metadata_payload)(ctx, rw, pl));
 
         metadata_bytes_left -= pl->payload_size;
-
-        current->metadata_count = p + 1;
         if (metadata_bytes_left == 0)
             break;
     }
-- 
2.47.2

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Re: [FFmpeg-devel] [PATCH] cbs_apv: Fix memory leak on metadata parse failure

[Mark Thompson]

On 14/05/2025 21:50, Mark Thompson wrote:
> Buffers are allocated inside some metadata types, so we must ensure
> that the object is visible to the free function before a parse failure.
> 
> Found by libFuzzer.
> ---
>  libavcodec/cbs_apv_syntax_template.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/libavcodec/cbs_apv_syntax_template.c b/libavcodec/cbs_apv_syntax_template.c
> index ca66349141..fc8a08ff31 100644
> --- a/libavcodec/cbs_apv_syntax_template.c
> +++ b/libavcodec/cbs_apv_syntax_template.c
> @@ -543,11 +543,11 @@ static int FUNC(metadata)(CodedBitstreamContext *ctx, RWContext *rw,
>              return AVERROR_INVALIDDATA;
>          }
>  
> +        current->metadata_count = p + 1;
> +
>          CHECK(FUNC(metadata_payload)(ctx, rw, pl));
>  
>          metadata_bytes_left -= pl->payload_size;
> -
> -        current->metadata_count = p + 1;
>          if (metadata_bytes_left == 0)
>              break;
>      }

Applied.  Simple application of libFuzzer to the decoder hasn't found anything else, either.

Thanks,

- Mark

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