libavcodec/flashsv.c:274: error: Integer Overflow L2
  (32 - [0, 64]):unsigned32 by call to `bitstream_read`.

libavcodec/flashsv.c:271:5: Call
269.         return -1;
270. 
271.     bitstream_init(&bc, avpkt->data, buf_size * 8);
         ^
272. 
273.     /* start to parse the bitstream */

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

libavcodec/flashsv.c:274:29: Call
272. 
273.     /* start to parse the bitstream */
274.     s->block_width  = 16 * (bitstream_read(&bc, 4) + 1);
                                 ^
275.     s->image_width  = bitstream_read(&bc, 12);
276.     s->block_height = 16 * (bitstream_read(&bc, 4) + 1);

libavcodec/bitstream.h:183:1: Parameter `n`
  181. 
  182. /* Return n bits from the buffer. n has to be in the 0-32 range. */
  183. static inline uint32_t bitstream_read(BitstreamContext *bc, unsigned n)
       ^
  184. {
  185.     if (!n)

libavcodec/bitstream.h:189:9: Call
  187. 
  188.     if (n > bc->bits_left) {
  189.         refill_32(bc);
               ^
  190.         if (bc->bits_left < 32)
  191.             bc->bits_left = n;

libavcodec/bitstream.h:60:1: <RHS trace>
58. }
59. 
60. static inline void refill_32(BitstreamContext *bc)
    ^
61. {
62.     if (bc->ptr >= bc->buffer_end)

libavcodec/bitstream.h:60:1: Parameter `bc->bits_left`
    58. }
    59. 
    60. static inline void refill_32(BitstreamContext *bc)
        ^
    61. {
    62.     if (bc->ptr >= bc->buffer_end)

libavcodec/bitstream.h:68:5: Binary operation: (32 - [0, 64]):unsigned32 by call to `bitstream_read` 
    66.     bc->bits       = (uint64_t)AV_RL32(bc->ptr) << bc->bits_left | bc->bits;
    67. #else
    68.     bc->bits       = bc->bits | (uint64_t)AV_RB32(bc->ptr) << (32 - bc->bits_left);
            ^
    69. #endif
    70.     bc->ptr       += 4;
