From 8313bbc30cead62dc549bd0ff70d04195c1d2e83 Mon Sep 17 00:00:00 2001
From: Nicholas Bishop <nbishop@nbishop.net>
Date: Sun, 7 May 2023 22:41:18 -0400
Subject: [PATCH] uefi: Clear the Vec in DevicePathBuilder::with_vec

Previously there was an implicit assumption that the `Vec` was empty; clear it
to ensure this.
---
 CHANGELOG.md                        | 1 +
 uefi/src/proto/device_path/build.rs | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8c167a0c4..83a40d4b8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -50,6 +50,7 @@
 - The `Revision` struct's one field is now public.
 - Renamed `CStr8::to_bytes` to `CStr8::as_bytes` and changed the semantics:
   The trailing null character is now always included in the returned slice.
+- `DevicePathBuilder::with_vec` now clears the `Vec` before use.
 
 ## uefi-macros - [Unreleased]
 
diff --git a/uefi/src/proto/device_path/build.rs b/uefi/src/proto/device_path/build.rs
index 63c731516..03e24b75e 100644
--- a/uefi/src/proto/device_path/build.rs
+++ b/uefi/src/proto/device_path/build.rs
@@ -83,8 +83,11 @@ impl<'a> DevicePathBuilder<'a> {
     }
 
     /// Create a builder backed by a `Vec`.
+    ///
+    /// The `Vec` is cleared before use.
     #[cfg(feature = "alloc")]
     pub fn with_vec(v: &'a mut Vec<u8>) -> Self {
+        v.clear();
         Self {
             storage: BuilderStorage::Vec(v),
         }