libavcodec/xan.c:135: error: Integer Overflow L2
  ([0, 64] - 1):unsigned32 by call to `bitstream_read_bit`.

libavcodec/xan.c:132:5: Call
130.         return AVERROR_INVALIDDATA;
131. 
132.     bitstream_init(&bc, ptr, ptr_len * 8);
         ^
133. 
134.     while (val != 0x16) {

libavcodec/bitstream.h:85:9: Assignment
  83.         bc->buffer    =
  84.         bc->ptr       = NULL;
  85.         bc->bits_left = 0;
              ^
  86.         return AVERROR_INVALIDDATA;
  87.     }

libavcodec/xan.c:135:37: Call
133. 
134.     while (val != 0x16) {
135.         unsigned idx = val - 0x17 + bitstream_read_bit(&bc) * byte;
                                         ^
136.         if (idx >= 2 * byte)
137.             return AVERROR_INVALIDDATA;

libavcodec/bitstream.h:145:1: Parameter `bc->bits_left`
  143. 
  144. /* Return one bit from the buffer. */
  145. static inline unsigned bitstream_read_bit(BitstreamContext *bc)
       ^
  146. {
  147.     if (!bc->bits_left)

libavcodec/bitstream.h:150:12: Call
  148.         refill_64(bc);
  149. 
  150.     return get_val(bc, 1);
                  ^
  151. }
  152. 

libavcodec/bitstream.h:130:1: <LHS trace>
128. }
129. 
130. static inline uint64_t get_val(BitstreamContext *bc, unsigned n)
     ^
131. {
132. #ifdef BITSTREAM_READER_LE

libavcodec/bitstream.h:130:1: Parameter `bc->bits_left`
    128. }
    129. 
    130. static inline uint64_t get_val(BitstreamContext *bc, unsigned n)
         ^
    131. {
    132. #ifdef BITSTREAM_READER_LE

libavcodec/bitstream.h:130:1: <RHS trace>
128. }
129. 
130. static inline uint64_t get_val(BitstreamContext *bc, unsigned n)
     ^
131. {
132. #ifdef BITSTREAM_READER_LE

libavcodec/bitstream.h:130:1: Parameter `n`
    128. }
    129. 
    130. static inline uint64_t get_val(BitstreamContext *bc, unsigned n)
         ^
    131. {
    132. #ifdef BITSTREAM_READER_LE

libavcodec/bitstream.h:139:5: Binary operation: ([0, 64] - 1):unsigned32 by call to `bitstream_read_bit` 
    137.     bc->bits <<= n;
    138. #endif
    139.     bc->bits_left -= n;
             ^
    140. 
    141.     return ret;
