PT-2026-107652 · Crates.Io · Wasapi
Published
2026-09-08
·
Updated
2026-09-08
None
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WaveFormat::parse is a safe function that takes a &WAVEFORMATEX, which is
only valid for reads of size of::<WAVEFORMATEX>() (18) bytes. When the header
has wFormatTag == WAVE FORMAT EXTENSIBLE and cbSize >= 22, the function
reinterprets the reference as a WAVEFORMATEXTENSIBLE and reads 40 bytes.
Nothing in the signature guarantees that the header sits at the start of a
larger buffer, so safe code can trigger an out-of-bounds read:rust
use wasapi::WaveFormat;
use windows::Win32::Media::Audio::WAVEFORMATEX;
use windows::Win32::Media::KernelStreaming::WAVE FORMAT EXTENSIBLE;
let header = WAVEFORMATEX {
wFormatTag: WAVE FORMAT EXTENSIBLE as u16,
nChannels: 2,
nSamplesPerSec: 48000,
nAvgBytesPerSec: 384000,
nBlockAlign: 8,
wBitsPerSample: 32,
cbSize: 22,
};
// Reads 22 bytes past the end of `header`.
let = WaveFormat::parse(&header);A more likely way to hit this is to copy the header out of a format pointer
returned by WASAPI (
let fmt = unsafe { *ptr };) and pass &fmt. The copy
keeps cbSize, but not the 22 bytes that follow it. The bytes read past the
end are returned as the channel mask and subformat of the parsed format.The flaw was corrected in commit
2562db7, released in 0.25.0. parse is now
an unsafe fn that takes a *const WAVEFORMATEX, and the caller must
guarantee that the pointer is valid for reads of
size of::<WAVEFORMATEX>() + cbSize bytes. WaveFormat::parse from blob bytes
(available since 0.23.0) is the safe alternative and checks the slice length
against cbSize. Found an issue in the description? Have something to add? Feel free to write us 👾
Related Identifiers
Affected Products
Wasapi