libavfilter/vf_overlay.c:120: error: Null Dereference
  pointer `pix_desc` last assigned on line 117 could be null and is dereferenced at line 120, column 15.

libavfilter/vf_overlay.c:114:1: start of procedure config_input_main()
112. }
113. 
114. static int config_input_main(AVFilterLink *inlink)
     ^
115. {
116.     OverlayContext *s = inlink->dst->priv;

libavfilter/vf_overlay.c:116:5: 
114. static int config_input_main(AVFilterLink *inlink)
115. {
116.     OverlayContext *s = inlink->dst->priv;
         ^
117.     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
118. 

libavfilter/vf_overlay.c:117:5: 
115. {
116.     OverlayContext *s = inlink->dst->priv;
117.     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
         ^
118. 
119.     av_image_fill_max_pixsteps(s->max_plane_step, NULL, pix_desc);

libavutil/pixdesc.c:1507:1: start of procedure av_pix_fmt_desc_get()
  1505. }
  1506. 
  1507. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1508. {
  1509.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1509:9: Taking false branch
  1507. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1508. {
  1509.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1510.         return NULL;
  1511.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1509:24: Taking true branch
  1507. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1508. {
  1509.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1510.         return NULL;
  1511.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1510:9: 
  1508. {
  1509.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1510.         return NULL;
                ^
  1511.     return &av_pix_fmt_descriptors[pix_fmt];
  1512. }

libavutil/pixdesc.c:1512:1: return from a call to av_pix_fmt_desc_get
  1510.         return NULL;
  1511.     return &av_pix_fmt_descriptors[pix_fmt];
  1512. }
        ^
  1513. 
  1514. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libavfilter/vf_overlay.c:119:5: Skipping av_image_fill_max_pixsteps(): empty list of specs
117.     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
118. 
119.     av_image_fill_max_pixsteps(s->max_plane_step, NULL, pix_desc);
         ^
120.     s->hsub = pix_desc->log2_chroma_w;
121.     s->vsub = pix_desc->log2_chroma_h;

libavfilter/vf_overlay.c:120:5: 
118. 
119.     av_image_fill_max_pixsteps(s->max_plane_step, NULL, pix_desc);
120.     s->hsub = pix_desc->log2_chroma_w;
         ^
121.     s->vsub = pix_desc->log2_chroma_h;
122. 
