From 29c127a0827c1d362bf3cef8f32498ab22046ef8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9=20Silva?=
<123550+andresilva@users.noreply.github.com>
Date: Tue, 28 Apr 2020 23:17:16 +0100
Subject: [PATCH] babe: fix overflow in check_equivocation (#5818)
---
substrate/client/consensus/slots/src/aux_schema.rs | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/substrate/client/consensus/slots/src/aux_schema.rs b/substrate/client/consensus/slots/src/aux_schema.rs
index df4772a8e92..d54190ca071 100644
--- a/substrate/client/consensus/slots/src/aux_schema.rs
+++ b/substrate/client/consensus/slots/src/aux_schema.rs
@@ -85,8 +85,8 @@ pub fn check_equivocation<C, H, P>(
P: Clone + Encode + Decode + PartialEq,
{
// We don't check equivocations for old headers out of our capacity.
- if slot_now - slot > MAX_SLOT_CAPACITY {
- return Ok(None)
+ if slot_now.saturating_sub(slot) > MAX_SLOT_CAPACITY {
+ return Ok(None);
}
// Key for this slot.
@@ -102,6 +102,11 @@ pub fn check_equivocation<C, H, P>(
let first_saved_slot = load_decode::<_, u64>(backend, &slot_header_start[..])?
.unwrap_or(slot);
+ if slot_now < first_saved_slot {
+ // The code below assumes that slots will be visited sequentially.
+ return Ok(None);
+ }
+
for (prev_header, prev_signer) in headers_with_sig.iter() {
// A proof of equivocation consists of two headers:
// 1) signed by the same voter,
@@ -114,7 +119,7 @@ pub fn check_equivocation<C, H, P>(
snd_header: header.clone(),
}));
} else {
- // We don't need to continue in case of duplicated header,
+ // We don't need to continue in case of duplicated header,
// since it's already saved and a possible equivocation
// would have been detected before.
return Ok(None)
--
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