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Fix correctness issues for detectors #66

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merged 2 commits into from
Jun 12, 2022
Merged

Fix correctness issues for detectors #66

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dca6e8b
Fix incorrect bounds checks for `is_cr2`
deuill Jun 7, 2022
1b5bef7
Fix integer overflow in `msooxml` detection
deuill Jun 7, 2022
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7 changes: 6 additions & 1 deletion src/matchers/doc.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -67,7 +67,12 @@ fn msooxml(buf: &[u8]) -> Option<DocType> {
// skip to the second local file header
// since some documents include a 520-byte extra field following the file
// header, we need to scan for the next header
let mut start_offset = (u32::from_le_bytes(buf[18..22].try_into().unwrap()) + 49) as usize;
let mut start_offset = match u32::from_le_bytes(buf[18..22].try_into().unwrap()).checked_add(49)
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@deuill deuill Jun 7, 2022 •
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Here's a file (generated by fuzz tests) that replicates this: overflow.docx

{
Some(int) => int as usize,
None => return None,
};

let idx = search(buf, start_offset, 6000)?;

// now skip to the *third* local file header; again, we need to scan due to a
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2 changes: 1 addition & 1 deletion src/matchers/image.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,7 @@ pub fn is_webp(buf: &[u8]) -> bool {

/// Returns whether a buffer is Canon CR2 image data.
pub fn is_cr2(buf: &[u8]) -> bool {
buf.len() > 9
buf.len() > 10
&& ((buf[0] == 0x49 && buf[1] == 0x49 && buf[2] == 0x2A && buf[3] == 0x0)
|| (buf[0] == 0x4D && buf[1] == 0x4D && buf[2] == 0x0 && buf[3] == 0x2A))
&& buf[8] == 0x43
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