[FFmpeg-devel] [PATCH 3/6] avformat/aviobuf: Don't use NULL as src for memcpy
James Almer
jamrial at gmail.com
Wed Sep 28 23:46:36 EEST 2022
On 9/28/2022 3:58 PM, Andreas Rheinhardt wrote:
> This might happen in avio_write() if size == 0
> when the direct codepath is taken. It is undefined behaviour
> according to the spec although it happens to work in practice.
> Fixes the webm-webvtt-remux FATE-test under UBSan.
>
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
> ---
> libavformat/aviobuf.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
> index b20b1a611a..5b6a42d7f4 100644
> --- a/libavformat/aviobuf.c
> +++ b/libavformat/aviobuf.c
> @@ -231,6 +231,8 @@ void ffio_fill(AVIOContext *s, int b, int64_t count)
>
> void avio_write(AVIOContext *s, const unsigned char *buf, int size)
> {
> + if (size <= 0)
> + return;
> if (s->direct && !s->update_checksum) {
> avio_flush(s);
> writeout(s, buf, size);
> @@ -246,7 +248,7 @@ void avio_write(AVIOContext *s, const unsigned char *buf, int size)
>
> buf += len;
> size -= len;
> - }
> + } while (size > 0);
Why are you adding this at the end of a similar while statement? Did you
mean to replace the previous one with do()?
> }
>
> void avio_flush(AVIOContext *s)
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