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limits to data_header.size when combining shreds' payloads (#16708) 

Shredder::deshred is ignoring data_header.size when combining shreds' payloads:
https://github.com/solana-labs/solana/blob/37b8587d4/ledger/src/shred.rs#L940-L961

Also adding more sanity checks on the alignment of data shreds indices.
This commit is contained in:
behzad nouri 2021-04-27 12:04:44 +00:00 committed by GitHub
parent 68d5aec55b
commit 0f3ac51cf1
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 29 additions and 28 deletions
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2
core/src/replay_stage.rs
View File

@ -2948,6 +2948,8 @@ pub(crate) mod tests {
let gibberish = [0xa5u8; PACKET_DATA_SIZE]; let gibberish = [0xa5u8; PACKET_DATA_SIZE];
let mut data_header = DataShredHeader::default(); let mut data_header = DataShredHeader::default();
data_header.flags |= DATA_COMPLETE_SHRED; data_header.flags |= DATA_COMPLETE_SHRED;
// Need to provide the right size for Shredder::deshred.
data_header.size = SIZE_OF_DATA_SHRED_PAYLOAD as u16;
let mut shred = Shred::new_empty_from_header( let mut shred = Shred::new_empty_from_header(
ShredCommonHeader::default(), ShredCommonHeader::default(),
data_header, data_header,

55
ledger/src/shred.rs
View File

@ -786,7 +786,7 @@ impl Shredder {
.iter() .iter()
.map(|shred| &shred.payload[..PAYLOAD_ENCODE_SIZE]) .map(|shred| &shred.payload[..PAYLOAD_ENCODE_SIZE])
.collect(); .collect();
let mut parity = vec![vec![0; PAYLOAD_ENCODE_SIZE]; num_coding]; let mut parity = vec![vec![0u8; PAYLOAD_ENCODE_SIZE]; num_coding];
Session::new(num_data, num_coding) Session::new(num_data, num_coding)
.unwrap() .unwrap()
.encode(&data, &mut parity[..]) .encode(&data, &mut parity[..])
@ -938,37 +938,36 @@ impl Shredder {
/// Combines all shreds to recreate the original buffer /// Combines all shreds to recreate the original buffer
pub fn deshred(shreds: &[Shred]) -> std::result::Result<Vec<u8>, reed_solomon_erasure::Error> { pub fn deshred(shreds: &[Shred]) -> std::result::Result<Vec<u8>, reed_solomon_erasure::Error> {
let num_data = shreds.len(); use reed_solomon_erasure::Error::TooFewDataShards;
const SHRED_DATA_OFFSET: usize = SIZE_OF_COMMON_SHRED_HEADER + SIZE_OF_DATA_SHRED_HEADER;
Self::verify_consistent_shred_payload_sizes(&"deshred()", shreds)?; Self::verify_consistent_shred_payload_sizes(&"deshred()", shreds)?;
let data_shred_bufs = { let index = shreds.first().ok_or(TooFewDataShards)?.index();
let first_index = shreds.first().unwrap().index() as usize; let aligned = shreds.iter().zip(index..).all(|(s, i)| s.index() == i);
let last_shred = shreds.last().unwrap(); let data_complete = {
let last_index = if last_shred.data_complete() || last_shred.last_in_slot() { let shred = shreds.last().unwrap();
last_shred.index() as usize shred.data_complete() || shred.last_in_slot()
} else {
0
};
if num_data.saturating_add(first_index) != last_index.saturating_add(1) {
return Err(reed_solomon_erasure::Error::TooFewDataShards);
}
shreds.iter().map(|shred| &shred.payload).collect()
}; };
if !data_complete || !aligned {
Ok(Self::reassemble_payload(num_data, data_shred_bufs)) return Err(TooFewDataShards);
} }
let data: Vec<_> = shreds
fn reassemble_payload(num_data: usize, data_shred_bufs: Vec<&Vec<u8>>) -> Vec<u8> {
let valid_data_len = SHRED_PAYLOAD_SIZE - SIZE_OF_CODING_SHRED_HEADERS;
data_shred_bufs[..num_data]
.iter() .iter()
.flat_map(|data| { .flat_map(|shred| {
let offset = SIZE_OF_COMMON_SHRED_HEADER + SIZE_OF_DATA_SHRED_HEADER; let size = shred.data_header.size as usize;
data[offset..valid_data_len].iter() let size = shred.payload.len().min(size);
let offset = SHRED_DATA_OFFSET.min(size);
shred.payload[offset..size].iter()
}) })
.cloned() .copied()
.collect() .collect();
if data.is_empty() {
// For backward compatibility. This is needed when the data shred
// payload is None, so that deserializing to Vec<Entry> results in
// an empty vector.
Ok(vec![0u8; SIZE_OF_DATA_SHRED_PAYLOAD])
} else {
Ok(data)
}
} }
fn verify_consistent_shred_payload_sizes( fn verify_consistent_shred_payload_sizes(