From 5795acffd8706e1cb584284ee5bb3a30986d0e75 Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ard.biesheuvel@arm.com>
Date: Tue, 27 Oct 2020 18:02:40 +0100
Subject: [PATCH 091/147] crypto/poly1305/asm: fix armv8 pointer authentication

PAC pointer authentication signs the return address against the value
of the stack pointer, to prevent stack overrun exploits from corrupting
the control flow. However, this requires that the AUTIASP is issued with
SP holding the same value as it held when the PAC value was generated.
The Poly1305 armv8 code got this wrong, resulting in crashes on PAC
capable hardware.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/13256)

(cherry picked from commit fcf6e9d056162d5af64c6f7209388a5c3be2ce57)
---
 crypto/poly1305/asm/poly1305-armv8.pl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crypto/poly1305/asm/poly1305-armv8.pl b/crypto/poly1305/asm/poly1305-armv8.pl
index d07494b..2a42b64 100755
--- a/crypto/poly1305/asm/poly1305-armv8.pl
+++ b/crypto/poly1305/asm/poly1305-armv8.pl
@@ -864,8 +864,8 @@ poly1305_blocks_neon:
 	st1	{$ACC4}[0],[$ctx]
 
 .Lno_data_neon:
-	.inst	0xd50323bf		// autiasp
 	ldr	x29,[sp],#80
+	.inst	0xd50323bf		// autiasp
 	ret
 .size	poly1305_blocks_neon,.-poly1305_blocks_neon
 
-- 
1.8.3.1

