From 75ef5232300a7d005578003c2dfc4d2b38cb7b8a Mon Sep 17 00:00:00 2001
From: Kornel <kornel@cloudflare.com>
Date: Wed, 1 Oct 2025 11:12:40 +0100
Subject: [PATCH] Safer CryptoBufferBuilder::build

---
 boring/src/ssl/callbacks.rs | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/boring/src/ssl/callbacks.rs b/boring/src/ssl/callbacks.rs
index ea0a73c2..f08409b3 100644
--- a/boring/src/ssl/callbacks.rs
+++ b/boring/src/ssl/callbacks.rs
@@ -16,7 +16,7 @@ use foreign_types::ForeignType;
 use foreign_types::ForeignTypeRef;
 use libc::{c_char, c_int, c_uchar, c_uint, c_void};
 use std::ffi::CStr;
-use std::mem::MaybeUninit;
+use std::mem::{self, MaybeUninit};
 use std::ptr;
 use std::slice;
 use std::str;
@@ -769,12 +769,8 @@ impl<'a> CryptoBufferBuilder<'a> {
             // Make sure all bytes in buffer initialized as required by Boring SSL.
             return Err(ErrorStack::internal_error_str("invalid len"));
         }
-        unsafe {
-            let mut result = ptr::null_mut();
-            ptr::swap(&mut self.buffer, &mut result);
-            std::mem::forget(self);
-            Ok(result)
-        }
+        // Drop is no-op if the buffer is null
+        Ok(mem::replace(&mut self.buffer, ptr::null_mut()))
     }
 }