libavcodec/gsmdec.c:92: error: Integer Overflow L2
  ([1, +oo] - 4):unsigned32 by call to `bitstream_read`.

libavcodec/gsmdec.c:92:13: Call
90.     case AV_CODEC_ID_GSM:
91.         bitstream_init(&bc, buf, buf_size * 8);
92.         if (bitstream_read(&bc, 4) != 0xd)
                ^
93.             av_log(avctx, AV_LOG_WARNING, "Missing GSM magic!\n");
94.         res = gsm_decode_block(avctx, samples, &bc, GSM_13000);

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:194:12: Call
  192.     }
  193. 
  194.     return get_val(bc, n);
                  ^
  195. }
  196. 

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: ([1, +oo] - 4):unsigned32 by call to `bitstream_read` 
    137.     bc->bits <<= n;
    138. #endif
    139.     bc->bits_left -= n;
             ^
    140. 
    141.     return ret;

static inline uint64_t get_val(BitstreamContext *bc, unsigned n)
{
#ifdef BITSTREAM_READER_LE
    uint64_t ret = bc->bits & ((UINT64_C(1) << n) - 1);
    bc->bits >>= n;
#else
    uint64_t ret = bc->bits >> (64 - n);
    bc->bits <<= n;
#endif
    bc->bits_left -= n;
    return ret;
}
['static int gsm_decode_frame(AVCodecContext *avctx, void *data,\n                            int *got_frame_ptr, AVPacket *avpkt)\n{\n    AVFrame *frame = data;\n    int res;\n    BitstreamContext bc;\n    const uint8_t *buf = avpkt->data;\n    int buf_size = avpkt->size;\n    int16_t *samples;\n    if (buf_size < avctx->block_align) {\n        av_log(avctx, AV_LOG_ERROR, "Packet is too small\\n");\n        return AVERROR_INVALIDDATA;\n    }\n    frame->nb_samples = avctx->frame_size;\n    if ((res = ff_get_buffer(avctx, frame, 0)) < 0) {\n        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\\n");\n        return res;\n    }\n    samples = (int16_t *)frame->data[0];\n    switch (avctx->codec_id) {\n    case AV_CODEC_ID_GSM:\n        bitstream_init(&bc, buf, buf_size * 8);\n        if (bitstream_read(&bc, 4) != 0xd)\n            av_log(avctx, AV_LOG_WARNING, "Missing GSM magic!\\n");\n        res = gsm_decode_block(avctx, samples, &bc, GSM_13000);\n        if (res < 0)\n            return res;\n        break;\n    case AV_CODEC_ID_GSM_MS:\n        res = ff_msgsm_decode_block(avctx, samples, buf,\n                                    (GSM_MS_BLOCK_SIZE - avctx->block_align) / 3);\n        if (res < 0)\n            return res;\n    }\n    *got_frame_ptr = 1;\n    return avctx->block_align;\n}', 'static inline uint32_t bitstream_read(BitstreamContext *bc, unsigned n)\n{\n    if (!n)\n        return 0;\n    if (n > bc->bits_left) {\n        refill_32(bc);\n        if (bc->bits_left < 32)\n            bc->bits_left = n;\n    }\n    return get_val(bc, n);\n}', 'static inline uint64_t get_val(BitstreamContext *bc, unsigned n)\n{\n#ifdef BITSTREAM_READER_LE\n    uint64_t ret = bc->bits & ((UINT64_C(1) << n) - 1);\n    bc->bits >>= n;\n#else\n    uint64_t ret = bc->bits >> (64 - n);\n    bc->bits <<= n;\n#endif\n    bc->bits_left -= n;\n    return ret;\n}']