libavfilter/vf_pad.c:146: error: Null Dereference
  pointer `pix_desc` last assigned on line 140 could be null and is dereferenced at line 146, column 17.

libavfilter/vf_pad.c:136:1: start of procedure config_input()
134. }
135. 
136. static int config_input(AVFilterLink *inlink)
     ^
137. {
138.     AVFilterContext *ctx = inlink->dst;

libavfilter/vf_pad.c:138:5: 
136. static int config_input(AVFilterLink *inlink)
137. {
138.     AVFilterContext *ctx = inlink->dst;
         ^
139.     PadContext *pad = ctx->priv;
140.     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);

libavfilter/vf_pad.c:139:5: 
137. {
138.     AVFilterContext *ctx = inlink->dst;
139.     PadContext *pad = ctx->priv;
         ^
140.     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
141.     uint8_t rgba_color[4];

libavfilter/vf_pad.c:140:5: 
138.     AVFilterContext *ctx = inlink->dst;
139.     PadContext *pad = ctx->priv;
140.     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
         ^
141.     uint8_t rgba_color[4];
142.     int ret, is_packed_rgba;

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_pad.c:146:5: 
144.     char *expr;
145. 
146.     pad->hsub = pix_desc->log2_chroma_w;
         ^
147.     pad->vsub = pix_desc->log2_chroma_h;
148. 
