libavcodec/dvbsubdec.c:481: error: Integer Overflow L2
  ([1, +oo] - 2):unsigned32 by call to `bitstream_read`.

libavcodec/dvbsubdec.c:481:34: Call
479.                 bits = bitstream_read_bit(&bc);
480.                 if (bits == 0) {
481.                     run_length = bitstream_read(&bc, 2) + 4;
                                      ^
482.                     bits       = bitstream_read(&bc, 4);
483. 

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] - 2):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 dvbsub_read_4bit_string(uint8_t *destbuf, int dbuf_len,\n                                   const uint8_t **srcbuf, int buf_size,\n                                   int non_mod, uint8_t *map_table)\n{\n    BitstreamContext bc;\n    int bits;\n    int run_length;\n    int pixels_read = 0;\n    bitstream_init(&bc, *srcbuf, buf_size << 3);\n    while (bitstream_tell(&bc) < buf_size << 3 && pixels_read < dbuf_len) {\n        bits = bitstream_read(&bc, 4);\n        if (bits) {\n            if (non_mod != 1 || bits != 1) {\n                if (map_table)\n                    *destbuf++ = map_table[bits];\n                else\n                    *destbuf++ = bits;\n            }\n            pixels_read++;\n        } else {\n            bits = bitstream_read_bit(&bc);\n            if (bits == 0) {\n                run_length = bitstream_read(&bc, 3);\n                if (run_length == 0) {\n                    *srcbuf += (bitstream_tell(&bc) + 7) >> 3;\n                    return pixels_read;\n                }\n                run_length += 2;\n                if (map_table)\n                    bits = map_table[0];\n                else\n                    bits = 0;\n                while (run_length-- > 0 && pixels_read < dbuf_len) {\n                    *destbuf++ = bits;\n                    pixels_read++;\n                }\n            } else {\n                bits = bitstream_read_bit(&bc);\n                if (bits == 0) {\n                    run_length = bitstream_read(&bc, 2) + 4;\n                    bits       = bitstream_read(&bc, 4);\n                    if (non_mod == 1 && bits == 1)\n                        pixels_read += run_length;\n                    else {\n                        if (map_table)\n                            bits = map_table[bits];\n                        while (run_length-- > 0 && pixels_read < dbuf_len) {\n                            *destbuf++ = bits;\n                            pixels_read++;\n                        }\n                    }\n                } else {\n                    bits = bitstream_read(&bc, 2);\n                    if (bits == 2) {\n                        run_length = bitstream_read(&bc, 4) + 9;\n                        bits       = bitstream_read(&bc, 4);\n                        if (non_mod == 1 && bits == 1)\n                            pixels_read += run_length;\n                        else {\n                            if (map_table)\n                                bits = map_table[bits];\n                            while (run_length-- > 0 && pixels_read < dbuf_len) {\n                                *destbuf++ = bits;\n                                pixels_read++;\n                            }\n                        }\n                    } else if (bits == 3) {\n                        run_length = bitstream_read(&bc, 8) + 25;\n                        bits = bitstream_read(&bc, 4);\n                        if (non_mod == 1 && bits == 1)\n                            pixels_read += run_length;\n                        else {\n                            if (map_table)\n                                bits = map_table[bits];\n                            while (run_length-- > 0 && pixels_read < dbuf_len) {\n                                *destbuf++ = bits;\n                                pixels_read++;\n                            }\n                        }\n                    } else if (bits == 1) {\n                        pixels_read += 2;\n                        if (map_table)\n                            bits = map_table[0];\n                        else\n                            bits = 0;\n                        if (pixels_read <= dbuf_len) {\n                            *destbuf++ = bits;\n                            *destbuf++ = bits;\n                        }\n                    } else {\n                        if (map_table)\n                            bits = map_table[0];\n                        else\n                            bits = 0;\n                        *destbuf++ = bits;\n                        pixels_read ++;\n                    }\n                }\n            }\n        }\n    }\n    if (bitstream_read(&bc, 8))\n        av_log(NULL, AV_LOG_ERROR, "DVBSub error: line overflow\\n");\n    *srcbuf += (bitstream_tell(&bc) + 7) >> 3;\n    return pixels_read;\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}']