libavcodec/4xm.c:508: error: Integer Overflow L2
  ([0, +oo] - [0, 15]):unsigned32 by call to `bitstream_read_xbits`.

libavcodec/4xm.c:483:1: Parameter `f->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:508:21: Call
506.             i += 16;
507.         } else {
508.             level = bitstream_read_xbits(&f->bc, code & 0xf);
                         ^
509.             i    += code >> 4;
510.             if (i >= 64) {

libavcodec/bitstream.h:281:1: Parameter `length`
  279. /* Read MPEG-1 dc-style VLC (sign bit + mantissa with no MSB).
  280.  * If MSB not set it is negative. */
  281. static inline int bitstream_read_xbits(BitstreamContext *bc, unsigned length)
       ^
  282. {
  283.     int32_t cache = bitstream_peek(bc, 32);

libavcodec/bitstream.h:285:5: Call
  283.     int32_t cache = bitstream_peek(bc, 32);
  284.     int sign = ~cache >> 31;
  285.     skip_remaining(bc, length);
           ^
  286. 
  287.     return ((((uint32_t)(sign ^ cache)) >> (32 - length)) ^ sign) - sign;

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] - [0, 15]):unsigned32 by call to `bitstream_read_xbits` 
    235.     bc->bits <<= n;
    236. #endif
    237.     bc->bits_left -= n;
             ^
    238. }
    239. 
