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#1244: reserve at most 64 MB for a file's entry before its data is read 

The entry's length comes from the file: a damaged or hostile one claiming 1 GB had it reserved
before a byte was unpacked.
This commit is contained in:
bflatastic 2026-10-12 10:36:27 +07:00
parent ecb4be19ba
commit ecf361c9d7
1 changed files with 4 additions and 1 deletions
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5
crates/format/src/unpack.rs
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@ -11,6 +11,8 @@ use crate::{BLOB_MAGIC, FormatError, MAX_BLOB, MAX_BLOBS, MAX_JSON, MAX_UNPACKED
/// Bytes unpacked at a time while looking for the end of the JSON.
const CHUNK: u64 = 64 << 10;
/// Most bytes reserved for an entry before any of it is unpacked.
const RESERVE_MAX: usize = 64 << 20;
fn damaged(e: impl std::fmt::Display) -> FormatError {
FormatError::NotVectorcraft(format!("damaged compressed data: {e}"))
@ -206,7 +208,8 @@ impl Stream<'_> {
}
let mut bytes = Vec::new();
let n = usize::try_from(len).map_err(|_| FormatError::TooBig)?;
bytes.try_reserve_exact(n).map_err(|_| FormatError::TooBig)?;
// The length is the file's word: reserve up to a bound, and let real data grow the rest.
bytes.try_reserve_exact(n.min(RESERVE_MAX)).map_err(|_| FormatError::TooBig)?;
let got = (&mut self.r).take(len).read_to_end(&mut bytes).map_err(damaged)?;
self.pos += got as u64;
Ok((got as u64 == len).then_some(bytes))