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fix: cap VecOf pre-allocation to prevent OOM on malformed input #570

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Merged
kvinwang merged 1 commit into from
Mar 19, 2026
Merged

fix: cap VecOf pre-allocation to prevent OOM on malformed input #570

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25 changes: 15 additions & 10 deletions cc-eventlog/src/codecs.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,12 +7,12 @@ use std::ops::Deref;
use scale::{Decode, Input};

#[derive(Clone, Debug, PartialEq, Eq)]
pub struct VecOf<I, T> {
pub struct VecOf<I, T, const MAX_LEN: usize = 65536> {
len: I,
inner: Vec<T>,
}

impl<I: Default, T> Default for VecOf<I, T> {
impl<I: Default, T, const MAX_LEN: usize> Default for VecOf<I, T, MAX_LEN> {
fn default() -> Self {
Self {
len: I::default(),
Expand All @@ -21,11 +21,16 @@ impl<I: Default, T> Default for VecOf<I, T> {
}
}

impl<I: Decode + Into<u32> + Copy, T: Decode> Decode for VecOf<I, T> {
impl<I: Decode + Into<u32> + Copy, T: Decode, const MAX_LEN: usize> Decode
for VecOf<I, T, MAX_LEN>
{
fn decode<In: Input>(input: &mut In) -> Result<Self, scale::Error> {
let decoded_len = I::decode(input)?;
let len = decoded_len.into() as usize;
let mut inner = Vec::with_capacity(len);
if len > MAX_LEN {
return Err("VecOf length exceeds upper bound".into());
}
let mut inner = Vec::with_capacity(len.min(1024));
for _ in 0..len {
inner.push(T::decode(input)?);
}
Expand All @@ -36,7 +41,7 @@ impl<I: Decode + Into<u32> + Copy, T: Decode> Decode for VecOf<I, T> {
}
}

impl<I, T> VecOf<I, T> {
impl<I, T, const MAX_LEN: usize> VecOf<I, T, MAX_LEN> {
pub fn into_inner(self) -> Vec<T> {
self.inner
}
Expand All @@ -49,28 +54,28 @@ impl<I, T> VecOf<I, T> {
}
}

impl<I, T> Deref for VecOf<I, T> {
impl<I, T, const MAX_LEN: usize> Deref for VecOf<I, T, MAX_LEN> {
type Target = Vec<T>;

fn deref(&self) -> &Self::Target {
&self.inner
}
}

impl<I, T> From<(I, Vec<T>)> for VecOf<I, T> {
impl<I, T, const MAX_LEN: usize> From<(I, Vec<T>)> for VecOf<I, T, MAX_LEN> {
fn from((len, vec): (I, Vec<T>)) -> Self {
Self { len, inner: vec }
}
}

impl<I, T> AsRef<[T]> for VecOf<I, T> {
impl<I, T, const MAX_LEN: usize> AsRef<[T]> for VecOf<I, T, MAX_LEN> {
fn as_ref(&self) -> &[T] {
&self.inner
}
}

impl<I, T> From<VecOf<I, T>> for Vec<T> {
fn from(value: VecOf<I, T>) -> Self {
impl<I, T, const MAX_LEN: usize> From<VecOf<I, T, MAX_LEN>> for Vec<T> {
fn from(value: VecOf<I, T, MAX_LEN>) -> Self {
value.inner
}
}
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