netdev - [PATCH] wireguard: allowedips: Prevent unaligned memory accesses

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Message-ID: <ZoV6Q6lWgVRqe7eh@p100>
Date: Wed, 3 Jul 2024 18:20:19 +0200
From: Helge Deller <deller@...nel.org>
To: "Jason A. Donenfeld" <Jason@...c4.com>, wireguard@...ts.zx2c4.com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-parisc@...r.kernel.org
Subject: [PATCH] wireguard: allowedips: Prevent unaligned memory accesses

On the parisc platform the Linux kernel issues kernel warnings because
swap_endian() tries to load a 128-bit IPv6 address from an unaligned
memory location:
 Kernel: unaligned access to 0x55f4688c in wg_allowedips_insert_v6+0x2c/0x80 [wireguard] (iir 0xf3010df)
 Kernel: unaligned access to 0x55f46884 in wg_allowedips_insert_v6+0x38/0x80 [wireguard] (iir 0xf2010dc)

Avoid such unaligned memory accesses by instead using the
get_unaligned_be64() helper macro.

Signed-off-by: Helge Deller <deller@....de>

diff --git a/drivers/net/wireguard/allowedips.c b/drivers/net/wireguard/allowedips.c
index 0ba714ca5185..daf967130b72 100644
--- a/drivers/net/wireguard/allowedips.c
+++ b/drivers/net/wireguard/allowedips.c
@@ -15,8 +15,8 @@ static void swap_endian(u8 *dst, const u8 *src, u8 bits)
 	if (bits == 32) {
 		*(u32 *)dst = be32_to_cpu(*(const __be32 *)src);
 	} else if (bits == 128) {
-		((u64 *)dst)[0] = be64_to_cpu(((const __be64 *)src)[0]);
-		((u64 *)dst)[1] = be64_to_cpu(((const __be64 *)src)[1]);
+		((u64 *)dst)[0] = get_unaligned_be64(src);
+		((u64 *)dst)[1] = get_unaligned_be64(src[8]);
 	}
 }