[FFmpeg-devel] [PATCH 2/5] avcodec/wavpack: Fix overflow in k=31

[Michael Niedermayer]

On Wed, Nov 30, 2022 at 09:39:44PM +0100, Paul B Mahol wrote:
> On 9/11/22, Michael Niedermayer <michael at niedermayer.cc> wrote:
> > Untested with "non fuzzed" samples as i have no such file
> >
> 
> Then create it.

the official WavPack-5.6.0 decoder has 2 alternative optimized codepathes
#ifdef USE_BITMASK_TABLES
    extras = bitset [bitcount] - maxcode - 1;
#else
    extras = (1 << bitcount) - maxcode - 1;
#endif

The 2nd path would result in the same 1<<32 which is undefined but luckily
the first seems hardcoded to be used it uses this table:

const uint32_t bitset [] = {
    1L << 0, 1L << 1, 1L << 2, 1L << 3,
    1L << 4, 1L << 5, 1L << 6, 1L << 7,
    1L << 8, 1L << 9, 1L << 10, 1L << 11,
    1L << 12, 1L << 13, 1L << 14, 1L << 15,
    1L << 16, 1L << 17, 1L << 18, 1L << 19,
    1L << 20, 1L << 21, 1L << 22, 1L << 23,
    1L << 24, 1L << 25, 1L << 26, 1L << 27,
    1L << 28, 1L << 29, 1L << 30, 1L << 31
};

here bitset[32] is out of array

Given above i suspect no valid file should use this. Otherwise something
seriously odd is going on.

also the subject has a typo its p=31 not k=31

thx

[...]

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