libavcodec/utils.c:516: error: Null Dereference
  pointer `buf` last assigned on line 505 could be null and is dereferenced at line 516, column 13.

libavcodec/utils.c:493:1: start of procedure avcodec_default_release_buffer()
491. }
492. 
493. void avcodec_default_release_buffer(AVCodecContext *s, AVFrame *pic)
     ^
494. {
495.     int i;

libavcodec/utils.c:497:5: 
495.     int i;
496.     InternalBuffer *buf, *last;
497.     AVCodecInternal *avci = s->internal;
         ^
498. 
499.     assert(s->codec_type == AVMEDIA_TYPE_VIDEO);

libavcodec/utils.c:499:5: 
497.     AVCodecInternal *avci = s->internal;
498. 
499.     assert(s->codec_type == AVMEDIA_TYPE_VIDEO);
         ^
500. 
501.     assert(pic->type == FF_BUFFER_TYPE_INTERNAL);

libavcodec/utils.c:501:5: 
499.     assert(s->codec_type == AVMEDIA_TYPE_VIDEO);
500. 
501.     assert(pic->type == FF_BUFFER_TYPE_INTERNAL);
         ^
502.     assert(avci->buffer_count);
503. 

libavcodec/utils.c:502:5: 
500. 
501.     assert(pic->type == FF_BUFFER_TYPE_INTERNAL);
502.     assert(avci->buffer_count);
         ^
503. 
504.     if (avci->buffer) {

libavcodec/utils.c:504:9: Taking true branch
502.     assert(avci->buffer_count);
503. 
504.     if (avci->buffer) {
             ^
505.         buf = NULL; /* avoids warning */
506.         for (i = 0; i < avci->buffer_count; i++) { //just 3-5 checks so is not worth to optimize

libavcodec/utils.c:505:9: 
503. 
504.     if (avci->buffer) {
505.         buf = NULL; /* avoids warning */
             ^
506.         for (i = 0; i < avci->buffer_count; i++) { //just 3-5 checks so is not worth to optimize
507.             buf = &avci->buffer[i];

libavcodec/utils.c:506:14: 
504.     if (avci->buffer) {
505.         buf = NULL; /* avoids warning */
506.         for (i = 0; i < avci->buffer_count; i++) { //just 3-5 checks so is not worth to optimize
                  ^
507.             buf = &avci->buffer[i];
508.             if (buf->data[0] == pic->data[0])

libavcodec/utils.c:506:21: Loop condition is false. Leaving loop
504.     if (avci->buffer) {
505.         buf = NULL; /* avoids warning */
506.         for (i = 0; i < avci->buffer_count; i++) { //just 3-5 checks so is not worth to optimize
                         ^
507.             buf = &avci->buffer[i];
508.             if (buf->data[0] == pic->data[0])

libavcodec/utils.c:511:9: 
509.                 break;
510.         }
511.         assert(i < avci->buffer_count);
             ^
512.         avci->buffer_count--;
513.         last = &avci->buffer[avci->buffer_count];

libavcodec/utils.c:512:9: 
510.         }
511.         assert(i < avci->buffer_count);
512.         avci->buffer_count--;
             ^
513.         last = &avci->buffer[avci->buffer_count];
514. 

libavcodec/utils.c:513:9: 
511.         assert(i < avci->buffer_count);
512.         avci->buffer_count--;
513.         last = &avci->buffer[avci->buffer_count];
             ^
514. 
515.         if (buf != last)

libavcodec/utils.c:515:13: Taking true branch
513.         last = &avci->buffer[avci->buffer_count];
514. 
515.         if (buf != last)
                 ^
516.             FFSWAP(InternalBuffer, *buf, *last);
517.     }

libavcodec/utils.c:516:13: 
514. 
515.         if (buf != last)
516.             FFSWAP(InternalBuffer, *buf, *last);
                 ^
517.     }
518. 

void avcodec_default_release_buffer(AVCodecContext *s, AVFrame *pic)
{
    int i;
    InternalBuffer *buf, *last;
    AVCodecInternal *avci = s->internal;
    assert(s->codec_type == AVMEDIA_TYPE_VIDEO);
    assert(pic->type == FF_BUFFER_TYPE_INTERNAL);
    assert(avci->buffer_count);
    if (avci->buffer) {
        buf = NULL;
        for (i = 0; i < avci->buffer_count; i++) {
            buf = &avci->buffer[i];
            if (buf->data[0] == pic->data[0])
                break;
        }
        assert(i < avci->buffer_count);
        avci->buffer_count--;
        last = &avci->buffer[avci->buffer_count];
        if (buf != last)
            FFSWAP(InternalBuffer, *buf, *last);
    }
    for (i = 0; i < AV_NUM_DATA_POINTERS; i++)
        pic->data[i] = NULL;
    if (s->debug & FF_DEBUG_BUFFERS)
        av_log(s, AV_LOG_DEBUG, "default_release_buffer called on pic %p, %d "
                                "buffers used\n", pic, avci->buffer_count);
}
['void avcodec_default_release_buffer(AVCodecContext *s, AVFrame *pic)\n{\n    int i;\n    InternalBuffer *buf, *last;\n    AVCodecInternal *avci = s->internal;\n    assert(s->codec_type == AVMEDIA_TYPE_VIDEO);\n    assert(pic->type == FF_BUFFER_TYPE_INTERNAL);\n    assert(avci->buffer_count);\n    if (avci->buffer) {\n        buf = NULL;\n        for (i = 0; i < avci->buffer_count; i++) {\n            buf = &avci->buffer[i];\n            if (buf->data[0] == pic->data[0])\n                break;\n        }\n        assert(i < avci->buffer_count);\n        avci->buffer_count--;\n        last = &avci->buffer[avci->buffer_count];\n        if (buf != last)\n            FFSWAP(InternalBuffer, *buf, *last);\n    }\n    for (i = 0; i < AV_NUM_DATA_POINTERS; i++)\n        pic->data[i] = NULL;\n    if (s->debug & FF_DEBUG_BUFFERS)\n        av_log(s, AV_LOG_DEBUG, "default_release_buffer called on pic %p, %d "\n                                "buffers used\\n", pic, avci->buffer_count);\n}']