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pixels: Fix webp detection (#35474)

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According to the riff_container specification, the suffix is only WEBP.
Additionally, this commit also verifies that the length of the byte
buffer matches the length declared by the riff header.

Source: https://developers.google.com/speed/webp/docs/riff_container

Signed-off-by: Jonathan Schwender <schwenderjonathan@gmail.com>
This commit is contained in:
Jonathan Schwender 2025-02-19 12:09:16 +01:00 • committed by GitHub
parent e5c9a0365d
commit 42e873e9d9
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1 changed files with 13 additions and 2 deletions
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15
components/pixels/lib.rs
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@ -243,7 +243,18 @@ fn is_ico(buffer: &[u8]) -> bool {
}
fn is_webp(buffer: &[u8]) -> bool {
buffer.starts_with(b"RIFF") && buffer.len() >= 14 && &buffer[8..14] == b"WEBPVP"
// https://developers.google.com/speed/webp/docs/riff_container
// First four bytes: `RIFF`, header size 12 bytes
if !buffer.starts_with(b"RIFF") || buffer.len() < 12 {
return false;
}
let size: [u8; 4] = [buffer[4], buffer[5], buffer[6], buffer[7]];
// Bytes 4..8 are a little endian u32 indicating
// > The size of the file in bytes, starting at offset 8.
// > The maximum value of this field is 2^32 minus 10 bytes and thus the size
// > of the whole file is at most 4 GiB minus 2 bytes.
let len: usize = u32::from_le_bytes(size) as usize;
buffer[8..].len() >= len && &buffer[8..12] == b"WEBP"
}
#[cfg(test)]
@ -257,7 +268,7 @@ mod test {
let jpeg = [0xff, 0xd8, 0xff];
let png = [0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A];
let webp = [
b'R', b'I', b'F', b'F', 0x01, 0x02, 0x03, 0x04, b'W', b'E', b'B', b'P', b'V', b'P',
b'R', b'I', b'F', b'F', 0x04, 0x00, 0x00, 0x00, b'W', b'E', b'B', b'P',
];
let bmp = [0x42, 0x4D];
let ico = [0x00, 0x00, 0x01, 0x00];