void ff_add_pixels_clamped_c(const int16_t *block, uint8_t *av_restrict pixels,
                             ptrdiff_t line_size)
{
    int i;

    /* read the pixels */
    for (i = 0; i < 8; i++) {
        pixels[0] = av_clip_uint8(pixels[0] + block[0]);
        pixels[1] = av_clip_uint8(pixels[1] + block[1]);
        pixels[2] = av_clip_uint8(pixels[2] + block[2]);
        pixels[3] = av_clip_uint8(pixels[3] + block[3]);
        pixels[4] = av_clip_uint8(pixels[4] + block[4]);
        pixels[5] = av_clip_uint8(pixels[5] + block[5]);
        pixels[6] = av_clip_uint8(pixels[6] + block[6]);
        pixels[7] = av_clip_uint8(pixels[7] + block[7]);
        pixels   += line_size;
        block    += 8;
    }
}

The product dereferences a pointer that it expects to be valid but is NULL.