avcodec/pixlet: Fix runtime error: signed integer overflow: 2147483647 + 32...

avcodec/pixlet: Fix runtime error: signed integer overflow: 2147483647 + 32 cannot be represented in type 'int'

Fixes: 1829/clusterfuzz-testcase-minimized-5527165321871360

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpegSigned-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/pixlet.c

@@ -594,6 +594,10 @@ static int pixlet_decode_frame(AVCodecContext *avctx, void *data,
     width  = bytestream2_get_be32(&ctx->gb);
     height = bytestream2_get_be32(&ctx->gb);
 
+    if (    width > INT_MAX - (1U << (NB_LEVELS + 1))
+        || height > INT_MAX - (1U << (NB_LEVELS + 1)))
+        return AVERROR_INVALIDDATA;
+
     w = FFALIGN(width,  1 << (NB_LEVELS + 1));
     h = FFALIGN(height, 1 << (NB_LEVELS + 1));