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fix: prevent unbounded allocation in header parsing #573

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fix: prevent unbounded allocation in header parsing #573

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27 changes: 27 additions & 0 deletions age/src/format.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,11 @@ const V1_MAGIC: &[u8] = b"v1";
const MAC_TAG: &[u8] = b"---";
const ENCODED_MAC_LENGTH: usize = 43;

/// Maximum header size to prevent unbounded memory allocation.
///
/// This matches the limit used by the reference Go implementation.
const MAX_HEADER_SIZE: usize = 64 * 1024; // 64 KiB

#[derive(Debug, PartialEq)]
pub(crate) struct HeaderV1 {
pub(crate) recipients: Vec<Stanza>,
Expand Down Expand Up @@ -118,6 +123,12 @@ impl Header {
// remainder of the input will be truncated.
let m = data.len();
let new_len = m + n.get();

// Prevent unbounded memory allocation.
if new_len > MAX_HEADER_SIZE {
break Err(DecryptError::InvalidHeader);
}

data.resize(new_len, 0);
input.read_exact(&mut data[m..new_len])?;
}
Expand Down Expand Up @@ -148,6 +159,11 @@ impl Header {
"Incomplete header",
)));
}

// Prevent unbounded memory allocation.
if data.len() > MAX_HEADER_SIZE {
break Err(DecryptError::InvalidHeader);
}
}
Err(_) => {
break Err(DecryptError::InvalidHeader);
Expand Down Expand Up @@ -176,6 +192,12 @@ impl Header {
// remainder of the input will be truncated.
let m = data.len();
let new_len = m + n.get();

// Prevent unbounded memory allocation.
if new_len > MAX_HEADER_SIZE {
break Err(DecryptError::InvalidHeader);
}

data.resize(new_len, 0);
input.read_exact(&mut data[m..new_len]).await?;
}
Expand Down Expand Up @@ -210,6 +232,11 @@ impl Header {
"Incomplete header",
)));
}

// Prevent unbounded memory allocation.
if data.len() > MAX_HEADER_SIZE {
break Err(DecryptError::InvalidHeader);
}
}
Err(_) => {
break Err(DecryptError::InvalidHeader);
Expand Down