avcodec/lcldec: Check that dimensions are a multiple of the subsample factors

Other dimensions would not work correctly currently,
also ask for a sample for files that fail this check.

This fixes an integer overflow leading to out of array
accesses.

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/lcldec.c

@@ -42,6 +42,7 @@
 #include <stdlib.h>
 
 #include "libavutil/mem.h"
+#include "libavutil/pixdesc.h"
 #include "avcodec.h"
 #include "bytestream.h"
 #include "internal.h"
@@ -482,6 +483,7 @@ static av_cold int decode_init(AVCodecContext *avctx)
     unsigned int max_basesize = FFALIGN(avctx->width,  4) *
                                 FFALIGN(avctx->height, 4);
     unsigned int max_decomp_size;
+    int subsample_h, subsample_v;
 
     if (avctx->extradata_size < 8) {
         av_log(avctx, AV_LOG_ERROR, "Extradata size too small.\n");
@@ -507,6 +509,10 @@ static av_cold int decode_init(AVCodecContext *avctx)
         max_decomp_size = max_basesize * 2;
         avctx->pix_fmt = AV_PIX_FMT_YUV422P;
         av_log(avctx, AV_LOG_DEBUG, "Image type is YUV 4:2:2.\n");
+        if (avctx->width % 4) {
+            avpriv_request_sample(avctx, "Unsupported dimensions\n");
+            return AVERROR_INVALIDDATA;
+        }
         break;
     case IMGTYPE_RGB24:
         c->decomp_size = basesize * 3;
@@ -537,6 +543,12 @@ static av_cold int decode_init(AVCodecContext *avctx)
         return AVERROR_INVALIDDATA;
     }
 
+    av_pix_fmt_get_chroma_sub_sample(avctx->pix_fmt, &subsample_h, &subsample_v);
+    if (avctx->width % (1<<subsample_h) || avctx->height % (1<<subsample_v)) {
+        avpriv_request_sample(avctx, "Unsupported dimensions\n");
+        return AVERROR_INVALIDDATA;
+    }
+
     /* Detect compression method */
     c->compression = (int8_t)avctx->extradata[5];
     switch (avctx->codec_id) {