avcodec/rawdec: check for side data before checking its size

Fixes valgrind warnings about usage of uninitialized values.

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: James Almer <jamrial@gmail.com>
(cherry picked from commit 51e329918d)

Changelog

@@ -2,6 +2,7 @@ Entries are sorted chronologically from oldest to youngest within each release,
 releases are sorted from youngest to oldest.
 
 version 3.0.5:
+- avcodec/rawdec: check for side data before checking its size
 - avcodec/flacdec: Fix undefined shift in decode_subframe()
 - avcodec/get_bits: Fix get_sbits_long(0)
 - avformat/ffmdec: Check media type for chunks

libavcodec/rawdec.c

@@ -386,7 +386,7 @@ static int raw_decode(AVCodecContext *avctx, void *data, int *got_frame,
         int pal_size;
         const uint8_t *pal = av_packet_get_side_data(avpkt, AV_PKT_DATA_PALETTE,
                                                      &pal_size);
-        if (pal_size != AVPALETTE_SIZE) {
+        if (pal && pal_size != AVPALETTE_SIZE) {
             av_log(avctx, AV_LOG_ERROR, "Palette size %d is wrong\n", pal_size);
             pal = NULL;
         }