libavcodec/h261dec.c:275: error: Integer Overflow L2
  ([1, +oo] - 8):unsigned32 by call to `bitstream_read`.

libavcodec/h261dec.c:275:17: Call
273.     if (s->mb_intra) {
274.         /* DC coef */
275.         level = bitstream_read(&s->bc, 8);
                     ^
276.         // 0 (00000000b) and -128 (10000000b) are FORBIDDEN
277.         if ((level & 0x7F) == 0) {

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] - 8):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 h261_decode_block(H261Context *h, int16_t *block, int n, int coded)\n{\n    MpegEncContext *const s = &h->s;\n    int code, level, i, j, run;\n    RLTable *rl = &ff_h261_rl_tcoeff;\n    const uint8_t *scan_table;\n    scan_table = s->intra_scantable.permutated;\n    if (s->mb_intra) {\n        level = bitstream_read(&s->bc, 8);\n        if ((level & 0x7F) == 0) {\n            av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\\n",\n                   level, s->mb_x, s->mb_y);\n            return -1;\n        }\n        if (level == 255)\n            level = 128;\n        block[0] = level;\n        i        = 1;\n    } else if (coded) {\n        int check = bitstream_peek(&s->bc, 2);\n        i = 0;\n        if (check & 0x2) {\n            bitstream_skip(&s->bc, 2);\n            block[0] = (check & 0x1) ? -1 : 1;\n            i        = 1;\n        }\n    } else {\n        i = 0;\n    }\n    if (!coded) {\n        s->block_last_index[n] = i - 1;\n        return 0;\n    }\n    for (;;) {\n        code = bitstream_read_vlc(&s->bc, rl->vlc.table, TCOEFF_VLC_BITS, 2);\n        if (code < 0) {\n            av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\\n",\n                   s->mb_x, s->mb_y);\n            return -1;\n        }\n        if (code == rl->n) {\n            run   = bitstream_read(&s->bc, 6);\n            level = bitstream_read_signed(&s->bc, 8);\n        } else if (code == 0) {\n            break;\n        } else {\n            run   = rl->table_run[code];\n            level = rl->table_level[code];\n            if (bitstream_read_bit(&s->bc))\n                level = -level;\n        }\n        i += run;\n        if (i >= 64) {\n            av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d\\n",\n                   s->mb_x, s->mb_y);\n            return -1;\n        }\n        j        = scan_table[i];\n        block[j] = level;\n        i++;\n    }\n    s->block_last_index[n] = i - 1;\n    return 0;\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}']