From 69ee702ba9fff989932972577f647e0b5cc6ae65 Mon Sep 17 00:00:00 2001
From: Gav <gavin@parity.io>
Date: Wed, 20 Sep 2023 14:10:14 +0100
Subject: [PATCH 1/2] Preimage: Check that at least one is upgraded

---
 substrate/frame/preimage/src/lib.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/substrate/frame/preimage/src/lib.rs b/substrate/frame/preimage/src/lib.rs
index e603f1a32e6a..4dda0207e62c 100644
--- a/substrate/frame/preimage/src/lib.rs
+++ b/substrate/frame/preimage/src/lib.rs
@@ -156,6 +156,8 @@ pub mod pallet {
 		NotRequested,
 		/// More than `MAX_HASH_UPGRADE_BULK_COUNT` hashes were requested to be upgraded at once.
 		TooMany,
+		/// Too few hashes were requested to be upgraded (i.e. zero).
+		TooFew,
 	}
 
 	/// A reason for this pallet placing a hold on funds.
@@ -242,6 +244,7 @@ pub mod pallet {
 			hashes: Vec<T::Hash>,
 		) -> DispatchResultWithPostInfo {
 			ensure_signed(origin)?;
+			ensure!(hashes.len() > 0, Error::<T>::TooFew);
 			ensure!(hashes.len() <= MAX_HASH_UPGRADE_BULK_COUNT as usize, Error::<T>::TooMany);
 
 			let updated = hashes.iter().map(Self::do_ensure_updated).filter(|b| *b).count() as u32;

From 4cf2e8e641008da3106045d337a0ebba98c24705 Mon Sep 17 00:00:00 2001
From: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Date: Wed, 20 Sep 2023 14:35:54 +0100
Subject: [PATCH 2/2] Fix bench

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
---
 substrate/frame/preimage/src/benchmarking.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/substrate/frame/preimage/src/benchmarking.rs b/substrate/frame/preimage/src/benchmarking.rs
index d7c643ff9042..d0c3404f40a9 100644
--- a/substrate/frame/preimage/src/benchmarking.rs
+++ b/substrate/frame/preimage/src/benchmarking.rs
@@ -216,7 +216,7 @@ benchmarks! {
 	}
 
 	ensure_updated {
-		let n in 0..MAX_HASH_UPGRADE_BULK_COUNT;
+		let n in 1..MAX_HASH_UPGRADE_BULK_COUNT;
 
 		let caller = funded_account::<T>();
 		let hashes = (0..n).map(|i| insert_old_unrequested::<T>(i)).collect::<Vec<_>>();