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fix panic in crc32 hash calc #222

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Oct 9, 2024
Merged

fix panic in crc32 hash calc #222

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119 changes: 119 additions & 0 deletions test-libz-rs-sys/src/deflate.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2323,5 +2323,124 @@ fn copy_uninitialized_window_section() {

let err = unsafe { deflateEnd(stream) };
assert_eq!(ReturnCode::from(err), ReturnCode::Ok);

dest
});
}

#[test]
fn crc32_hash_calc_uninitialized_memory() {
// by default the `Crc32HashCalc::insert_string` function tries to read some uninitialized
// bytes in this case. That panicked before, and we now handle it properly.
//
// see https://github.com/trifectatechfoundation/zlib-rs/issues/219

let mut source = [
96, 48, 113, 0, 25, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 71, 0, 0, 0, 0, 0, 0, 7,
0, 0, 0, 64, 0, 0, 0, 38, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 86, 86, 86, 86, 86, 86, 86, 86,
86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86, 86,
86, 86, 0, 0, 0, 0, 121, 31, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 121, 31, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 0, 0, 0, 0, 0, 1, 0, 0, 0, 121, 31, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 64, 0, 0, 121, 31, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 121, 31, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
];

let config = DeflateConfig {
level: 0,
method: Method::Deflated,
window_bits: 31,
mem_level: 3,
strategy: Strategy::Default,
};

assert_eq_rs_ng!({
let mut stream = MaybeUninit::zeroed();

let err = unsafe {
deflateInit2_(
stream.as_mut_ptr(),
config.level,
config.method as i32,
config.window_bits,
config.mem_level,
config.strategy as i32,
zlibVersion(),
core::mem::size_of::<z_stream>() as c_int,
)
};
assert_eq!(ReturnCode::from(err), ReturnCode::Ok);

let stream = unsafe { stream.assume_init_mut() };

let buf_size = unsafe { deflateBound(stream, source.len() as _) };

let mut dest = vec![0; buf_size as usize];
let chunk = 2u32;
let flush = DeflateFlush::NoFlush;

stream.next_in = source.as_mut_ptr().cast();
stream.avail_in = chunk; // First chunk.
stream.next_out = dest.as_mut_ptr().cast();
stream.avail_out = dest.len().try_into().unwrap();

// Deflate first chunk.
let err = unsafe { deflate(stream, flush as i32) };
assert_eq!(ReturnCode::from(err), ReturnCode::Ok);

// Change the parameters.
let new_level = 4;
let err = unsafe { deflateParams(stream, new_level, config.strategy as _) };
match ReturnCode::from(err) {
ReturnCode::Ok => {}
ReturnCode::BufError => {
// Flushing the current pending data may run us out of buffer space.
// Worst case double the buffer size.
let add_space = Ord::min(chunk, buf_size as u32);
dest.resize(dest.len() + add_space as usize, 0);

// If extend() reallocates, it may have moved in memory.
stream.next_out = dest.as_mut_ptr();
stream.avail_out += add_space;

let err = unsafe { deflateParams(stream, new_level, config.strategy as _) };
assert_eq!(ReturnCode::from(err), ReturnCode::Ok);
}
err => panic!("fatal {:?}", err),
}

// Deflate the rest in chunks.
let mut left: u32 = source.len() as u32 - chunk;
while left > 0 {
// Write the chunk.
let avail = Ord::min(chunk, left);
stream.avail_in = avail;
let err = unsafe { deflate(stream, flush as i32) };
match ReturnCode::from(err) {
ReturnCode::Ok => {
left -= avail;
}
ReturnCode::BufError => {
// Worst case double the buffer size.
let add_space = Ord::min(chunk, buf_size as u32);
dest.resize(dest.len() + add_space as usize, 0);

// If extend() reallocates, it may have moved in memory.
stream.next_out = dest.as_mut_ptr();
stream.avail_out += add_space;

left -= avail - stream.avail_in;
}
err => panic!("fatal {:?}", err),
}
}

assert_eq!(left, 0);

dest
});
}
10 changes: 8 additions & 2 deletions zlib-rs/src/deflate/hash_calc.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -62,8 +62,11 @@ impl StandardHashCalc {
pub fn insert_string(state: &mut State, string: usize, count: usize) {
let slice = &state.window.filled()[string + Self::HASH_CALC_OFFSET..];

// it can happen that insufficient bytes are initialized
// .take(count) generates worse assembly
for (i, w) in slice[..count + 3].windows(4).enumerate() {
let slice = &slice[..Ord::min(slice.len(), count + 3)];

for (i, w) in slice.windows(4).enumerate() {
let idx = string as u16 + i as u16;

let val = u32::from_le_bytes(w.try_into().unwrap());
Expand Down Expand Up @@ -205,8 +208,11 @@ impl Crc32HashCalc {
pub unsafe fn insert_string(state: &mut State, string: usize, count: usize) {
let slice = &state.window.filled()[string + Self::HASH_CALC_OFFSET..];

// it can happen that insufficient bytes are initialized
// .take(count) generates worse assembly
for (i, w) in slice[..count + 3].windows(4).enumerate() {
let slice = &slice[..Ord::min(slice.len(), count + 3)];

for (i, w) in slice.windows(4).enumerate() {
let idx = string as u16 + i as u16;

let val = u32::from_le_bytes(w.try_into().unwrap());
Expand Down
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