Support <8-bit ILBM uncompressed bitmaps

Originally committed as revision 21846 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/iff.c

@@ -114,6 +114,7 @@ static int decode_frame_ilbm(AVCodecContext *avctx,
     IffContext *s = avctx->priv_data;
     const uint8_t *buf = avpkt->data;
     int buf_size = avpkt->size;
+    const uint8_t *buf_end = buf+buf_size;
     int y, plane;
 
     if (avctx->reget_buffer(avctx, &s->frame) < 0){
@@ -121,19 +122,14 @@ static int decode_frame_ilbm(AVCodecContext *avctx,
         return -1;
     }
 
-    if (buf_size < avctx->width * avctx->height) {
-        av_log(avctx, AV_LOG_ERROR, "buffer underflow\n");
-        return -1;
-    }
-
     for(y = 0; y < avctx->height; y++ ) {
         uint8_t *row = &s->frame.data[0][ y*s->frame.linesize[0] ];
         memset(row, 0, avctx->pix_fmt == PIX_FMT_PAL8 ? avctx->width : (avctx->width * 4));
-        for (plane = 0; plane < avctx->bits_per_coded_sample; plane++) {
+        for (plane = 0; plane < avctx->bits_per_coded_sample && buf < buf_end; plane++) {
             if (avctx->pix_fmt == PIX_FMT_PAL8) {
-                decodeplane8(row, buf, s->planesize, avctx->bits_per_coded_sample, plane);
+                decodeplane8(row, buf, FFMIN(s->planesize, buf_end - buf), avctx->bits_per_coded_sample, plane);
             } else { // PIX_FMT_BGR32
-                decodeplane32(row, buf, s->planesize, avctx->bits_per_coded_sample, plane);
+                decodeplane32(row, buf, FFMIN(s->planesize, buf_end - buf), avctx->bits_per_coded_sample, plane);
             }
             buf += s->planesize;
         }