avcodec/webp: Always set pix_fmt

Fixes: out of array access
Fixes: 1434/clusterfuzz-testcase-minimized-6314998085189632
Fixes: 1435/clusterfuzz-testcase-minimized-6483783723253760

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg
Reviewed-by: "Ronald S. Bultje" <rsbultje@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
void filter_mb(VP8Context *s, uint8_t *dst[3], VP8FilterStrength *f,
               int mb_x, int mb_y, int is_vp7)
{
    int mbedge_lim, bedge_lim_y, bedge_lim_uv, hev_thresh;
    int filter_level = f->filter_level;
    int inner_limit = f->inner_limit;
    int inner_filter = f->inner_filter;
    ptrdiff_t linesize   = s->linesize;
    ptrdiff_t uvlinesize = s->uvlinesize;
    static const uint8_t hev_thresh_lut[2][64] = {
        { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1,
          2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
          3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
          3, 3, 3, 3 },
        { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1,
          1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
          2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
          2, 2, 2, 2 }
    };

    if (!filter_level)
        return;

    if (is_vp7) {
        bedge_lim_y  = filter_level;
        bedge_lim_uv = filter_level * 2;
        mbedge_lim   = filter_level + 2;
    } else {
        bedge_lim_y  =
        bedge_lim_uv = filter_level * 2 + inner_limit;
        mbedge_lim   = bedge_lim_y + 4;
    }

    hev_thresh = hev_thresh_lut[s->keyframe][filter_level];

    if (mb_x) {
        s->vp8dsp.vp8_h_loop_filter16y(dst[0], linesize,
                                       mbedge_lim, inner_limit, hev_thresh);
        s->vp8dsp.vp8_h_loop_filter8uv(dst[1], dst[2], uvlinesize,
                                       mbedge_lim, inner_limit, hev_thresh);
    }

#define H_LOOP_FILTER_16Y_INNER(cond)                                         \
    if (cond && inner_filter) {                                               \
        s->vp8dsp.vp8_h_loop_filter16y_inner(dst[0] +  4, linesize,           \
                                             bedge_lim_y, inner_limit,        \
                                             hev_thresh);                     \
        s->vp8dsp.vp8_h_loop_filter16y_inner(dst[0] +  8, linesize,           \
                                             bedge_lim_y, inner_limit,        \
                                             hev_thresh);                     \
        s->vp8dsp.vp8_h_loop_filter16y_inner(dst[0] + 12, linesize,           \
                                             bedge_lim_y, inner_limit,        \
                                             hev_thresh);                     \
        s->vp8dsp.vp8_h_loop_filter8uv_inner(dst[1] +  4, dst[2] + 4,         \
                                             uvlinesize,  bedge_lim_uv,       \
                                             inner_limit, hev_thresh);        \
    }

    H_LOOP_FILTER_16Y_INNER(!is_vp7)

    if (mb_y) {
        s->vp8dsp.vp8_v_loop_filter16y(dst[0], linesize,
                                       mbedge_lim, inner_limit, hev_thresh);
        s->vp8dsp.vp8_v_loop_filter8uv(dst[1], dst[2], uvlinesize,
                                       mbedge_lim, inner_limit, hev_thresh);
    }

    if (inner_filter) {
        s->vp8dsp.vp8_v_loop_filter16y_inner(dst[0] +  4 * linesize,
                                             linesize, bedge_lim_y,
                                             inner_limit, hev_thresh);
        s->vp8dsp.vp8_v_loop_filter16y_inner(dst[0] +  8 * linesize,
                                             linesize, bedge_lim_y,
                                             inner_limit, hev_thresh);
        s->vp8dsp.vp8_v_loop_filter16y_inner(dst[0] + 12 * linesize,
                                             linesize, bedge_lim_y,
                                             inner_limit, hev_thresh);
        s->vp8dsp.vp8_v_loop_filter8uv_inner(dst[1] +  4 * uvlinesize,
                                             dst[2] +  4 * uvlinesize,
                                             uvlinesize, bedge_lim_uv,
                                             inner_limit, hev_thresh);
    }

    H_LOOP_FILTER_16Y_INNER(is_vp7)
}

void filter_mb(VP8Context *s, uint8_t *dst[3], VP8FilterStrength *f,
               int mb_x, int mb_y, int is_vp7)
{
    int mbedge_lim, bedge_lim_y, bedge_lim_uv, hev_thresh;
    int filter_level = f->filter_level;
    int inner_limit = f->inner_limit;
    int inner_filter = f->inner_filter;
    ptrdiff_t linesize   = s->linesize;
    ptrdiff_t uvlinesize = s->uvlinesize;
    static const uint8_t hev_thresh_lut[2][64] = {
        { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1,
          2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
          3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
          3, 3, 3, 3 },
        { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1,
          1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
          2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
          2, 2, 2, 2 }
    };

    if (!filter_level)
        return;

    if (is_vp7) {
        bedge_lim_y  = filter_level;
        bedge_lim_uv = filter_level * 2;
        mbedge_lim   = filter_level + 2;
    } else {
        bedge_lim_y  =
        bedge_lim_uv = filter_level * 2 + inner_limit;
        mbedge_lim   = bedge_lim_y + 4;
    }

    hev_thresh = hev_thresh_lut[s->keyframe][filter_level];

    if (mb_x) {
        s->vp8dsp.vp8_h_loop_filter16y(dst[0], linesize,
                                       mbedge_lim, inner_limit, hev_thresh);
        s->vp8dsp.vp8_h_loop_filter8uv(dst[1], dst[2], uvlinesize,
                                       mbedge_lim, inner_limit, hev_thresh);
    }

#define H_LOOP_FILTER_16Y_INNER(cond)                                         \
    if (cond && inner_filter) {                                               \
        s->vp8dsp.vp8_h_loop_filter16y_inner(dst[0] +  4, linesize,           \
                                             bedge_lim_y, inner_limit,        \
                                             hev_thresh);                     \
        s->vp8dsp.vp8_h_loop_filter16y_inner(dst[0] +  8, linesize,           \
                                             bedge_lim_y, inner_limit,        \
                                             hev_thresh);                     \
        s->vp8dsp.vp8_h_loop_filter16y_inner(dst[0] + 12, linesize,           \
                                             bedge_lim_y, inner_limit,        \
                                             hev_thresh);                     \
        s->vp8dsp.vp8_h_loop_filter8uv_inner(dst[1] +  4, dst[2] + 4,         \
                                             uvlinesize,  bedge_lim_uv,       \
                                             inner_limit, hev_thresh);        \
    }

    H_LOOP_FILTER_16Y_INNER(!is_vp7)

    if (mb_y) {
        s->vp8dsp.vp8_v_loop_filter16y(dst[0], linesize,
                                       mbedge_lim, inner_limit, hev_thresh);
        s->vp8dsp.vp8_v_loop_filter8uv(dst[1], dst[2], uvlinesize,
                                       mbedge_lim, inner_limit, hev_thresh);
    }

    if (inner_filter) {
        s->vp8dsp.vp8_v_loop_filter16y_inner(dst[0] +  4 * linesize,
                                             linesize, bedge_lim_y,
                                             inner_limit, hev_thresh);
        s->vp8dsp.vp8_v_loop_filter16y_inner(dst[0] +  8 * linesize,
                                             linesize, bedge_lim_y,
                                             inner_limit, hev_thresh);
        s->vp8dsp.vp8_v_loop_filter16y_inner(dst[0] + 12 * linesize,
                                             linesize, bedge_lim_y,
                                             inner_limit, hev_thresh);
        s->vp8dsp.vp8_v_loop_filter8uv_inner(dst[1] +  4 * uvlinesize,
                                             dst[2] +  4 * uvlinesize,
                                             uvlinesize, bedge_lim_uv,
                                             inner_limit, hev_thresh);
    }

    H_LOOP_FILTER_16Y_INNER(is_vp7)
}
