libavcodec/4xm.c:580: error: Integer Overflow L2
  ([0, +oo] - 9):unsigned32 by call to `decode_i_block`.

libavcodec/4xm.c:572:1: Parameter `f->pre_bc.bits_left`
570. }
571. 
572. static int decode_i_mb(FourXContext *f)
     ^
573. {
574.     int ret;

libavcodec/4xm.c:580:20: Call
578. 
579.     for (i = 0; i < 6; i++)
580.         if ((ret = decode_i_block(f, f->block[i])) < 0)
                        ^
581.             return ret;
582. 

libavcodec/4xm.c:483:1: Parameter `f->pre_bc.bits_left`
  481.  * Note this is almost identical to MJPEG.
  482.  */
  483. static int decode_i_block(FourXContext *f, int16_t *block)
       ^
  484. {
  485.     int code, i, j, level, val;

libavcodec/4xm.c:488:11: Call
  486. 
  487.     /* DC coef */
  488.     val = bitstream_read_vlc(&f->pre_bc, f->pre_vlc.table, ACDC_VLC_BITS, 3);
                 ^
  489.     if (val >> 4)
  490.         av_log(f->avctx, AV_LOG_ERROR, "error dc run != 0\n");

libavcodec/bitstream.h:313:1: Parameter `bits`
    311.  * If the VLC code is invalid and max_depth > 1, then the number of bits removed
    312.  * is undefined. */
    313. static inline int bitstream_read_vlc(BitstreamContext *bc, VLC_TYPE (*table)[2],
         ^
    314.                                      int bits, int max_depth)
    315. {

libavcodec/bitstream.h:322:9: Call
    320. 
    321.     if (max_depth > 1 && n < 0) {
    322.         skip_remaining(bc, bits);
                 ^
    323.         code = set_idx(bc, code, &n, &nb_bits, table);
    324.         if (max_depth > 2 && n < 0) {

libavcodec/bitstream.h:230:1: <LHS trace>
228. }
229. 
230. static inline void skip_remaining(BitstreamContext *bc, unsigned n)
     ^
231. {
232. #ifdef BITSTREAM_READER_LE

libavcodec/bitstream.h:230:1: Parameter `bc->bits_left`
      228. }
      229. 
      230. static inline void skip_remaining(BitstreamContext *bc, unsigned n)
           ^
      231. {
      232. #ifdef BITSTREAM_READER_LE

libavcodec/bitstream.h:230:1: <RHS trace>
228. }
229. 
230. static inline void skip_remaining(BitstreamContext *bc, unsigned n)
     ^
231. {
232. #ifdef BITSTREAM_READER_LE

libavcodec/bitstream.h:230:1: Parameter `n`
      228. }
      229. 
      230. static inline void skip_remaining(BitstreamContext *bc, unsigned n)
           ^
      231. {
      232. #ifdef BITSTREAM_READER_LE

libavcodec/bitstream.h:237:5: Binary operation: ([0, +oo] - 9):unsigned32 by call to `decode_i_block` 
      235.     bc->bits <<= n;
      236. #endif
      237.     bc->bits_left -= n;
               ^
      238. }
      239. 
