On 5 January 2012 22:15, Janne Grunau <[email protected]> wrote:
> Prevents null ptr derefence for negative sizes.
> ---
>  libavcodec/truemotion2.c |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
>
> diff --git a/libavcodec/truemotion2.c b/libavcodec/truemotion2.c
> index 8d72bb6..4045342 100644
> --- a/libavcodec/truemotion2.c
> +++ b/libavcodec/truemotion2.c
> @@ -272,6 +272,8 @@ static int tm2_read_stream(TM2Context *ctx, const uint8_t 
> *buf, int stream_id, i
>             len = AV_RB32(buf); buf += 4; cur += 4;
>         }
>         if(len > 0) {
> +            if (skip <= cur)
> +                return -1;
>             init_get_bits(&ctx->gb, buf, (skip - cur) * 8);
>             if(tm2_read_deltas(ctx, stream_id) == -1)
>                 return -1;
> @@ -286,6 +288,8 @@ static int tm2_read_stream(TM2Context *ctx, const uint8_t 
> *buf, int stream_id, i
>     buf += 4; cur += 4;
>     buf += 4; cur += 4; /* unused by decoder */
>
> +    if (skip <= cur)
> +        return -1;
>     init_get_bits(&ctx->gb, buf, (skip - cur) * 8);
>     if(tm2_build_huff_table(ctx, &codes) == -1)
>         return -1;
> @@ -303,6 +307,8 @@ static int tm2_read_stream(TM2Context *ctx, const uint8_t 
> *buf, int stream_id, i
>     ctx->tok_lens[stream_id] = toks;
>     len = AV_RB32(buf); buf += 4; cur += 4;
>     if(len > 0) {
> +        if (skip <= cur)
> +            return -1;
>         init_get_bits(&ctx->gb, buf, (skip - cur) * 8);
>         for(i = 0; i < toks; i++) {
>             if (get_bits_left(&ctx->gb) <= 0) {
> --

looks OK
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