[FFmpeg-devel] [PATCH] avcodec/aacenc: Avoid 0 lambda

[Anton Khirnov]

Quoting Michael Niedermayer (2021-05-28 22:15:51)
> Fixes: Ticket8003
> Fixes: CVE-2020-20453
> 
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>  libavcodec/aacenc.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/libavcodec/aacenc.c b/libavcodec/aacenc.c
> index aa223cf25f..e80591ba86 100644
> --- a/libavcodec/aacenc.c
> +++ b/libavcodec/aacenc.c
> @@ -28,6 +28,7 @@
>   *              TODOs:
>   * add sane pulse detection
>   ***********************************/
> +#include <float.h>
>  
>  #include "libavutil/libm.h"
>  #include "libavutil/float_dsp.h"
> @@ -852,7 +853,7 @@ static int aac_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
>                  /* Not so fast though */
>                  ratio = sqrtf(ratio);
>              }
> -            s->lambda = FFMIN(s->lambda * ratio, 65536.f);
> +            s->lambda = av_clipf(s->lambda * ratio, FLT_MIN, 65536.f);

Would FLT_EPSILON not be more appropriate? IIUC FLT_MIN is still
effectively zero.

-- 
Anton Khirnov