libavfilter/vf_drawbox.c:82: error: Null Dereference
  pointer `desc` last assigned on line 80 could be null and is dereferenced at line 82, column 21.

libavfilter/vf_drawbox.c:77:1: start of procedure config_input()
75. }
76. 
77. static int config_input(AVFilterLink *inlink)
    ^
78. {
79.     DrawBoxContext *drawbox = inlink->dst->priv;

libavfilter/vf_drawbox.c:79:5: 
77. static int config_input(AVFilterLink *inlink)
78. {
79.     DrawBoxContext *drawbox = inlink->dst->priv;
        ^
80.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
81. 

libavfilter/vf_drawbox.c:80:5: 
78. {
79.     DrawBoxContext *drawbox = inlink->dst->priv;
80.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
        ^
81. 
82.     drawbox->hsub = desc->log2_chroma_w;

libavutil/pixdesc.c:1464:1: start of procedure av_pix_fmt_desc_get()
  1462. }
  1463. 
  1464. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1466:9: Taking false branch
  1464. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1467.         return NULL;
  1468.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1466:24: Taking true branch
  1464. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1467.         return NULL;
  1468.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1467:9: 
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1467.         return NULL;
                ^
  1468.     return &av_pix_fmt_descriptors[pix_fmt];
  1469. }

libavutil/pixdesc.c:1469:1: return from a call to av_pix_fmt_desc_get
  1467.         return NULL;
  1468.     return &av_pix_fmt_descriptors[pix_fmt];
  1469. }
        ^
  1470. 
  1471. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libavfilter/vf_drawbox.c:82:5: 
80.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
81. 
82.     drawbox->hsub = desc->log2_chroma_w;
        ^
83.     drawbox->vsub = desc->log2_chroma_h;
84. 
