linux-kernel - [PATCH 6.15 025/192] arm64/mm: Drop wrong writes into TCR2

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250715130815.874397237@linuxfoundation.org>
Date: Tue, 15 Jul 2025 15:12:00 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: stable@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	patches@...ts.linux.dev,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Ryan Roberts <ryan.roberts@....com>,
	Marc Zyngier <maz@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Anshuman Khandual <anshuman.khandual@....com>,
	Sasha Levin <sashal@...nel.org>
Subject: [PATCH 6.15 025/192] arm64/mm: Drop wrong writes into TCR2_EL1

6.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Anshuman Khandual <anshuman.khandual@....com>

[ Upstream commit 9dd1757493416310a5e71146a08bc228869f8dae ]

Register X0 contains PIE_E1_ASM and should not be written into REG_TCR2_EL1
which could have an adverse impact otherwise. This has remained undetected
till now probably because current value for PIE_E1_ASM (0xcc880e0ac0800000)
clears TCR2_EL1 which again gets set subsequently with 'tcr2' after testing
for FEAT_TCR2.

Drop this unwarranted 'msr' which is a stray change from an earlier commit.
This line got re-introduced when rebasing on top of the commit 926b66e2ebc8
("arm64: setup: name 'tcr2' register").

Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will@...nel.org>
Cc: Ryan Roberts <ryan.roberts@....com>
Cc: Marc Zyngier <maz@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org
Fixes: 7052e808c446 ("arm64/sysreg: Get rid of the TCR2_EL1x SysregFields")
Acked-by: Marc Zyngier <maz@...nel.org>
Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
Link: https://lore.kernel.org/r/20250704063812.298914-1-anshuman.khandual@arm.com
Signed-off-by: Will Deacon <will@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm64/mm/proc.S | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index fb30c8804f87b..46a18af52980d 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -533,7 +533,6 @@ alternative_else_nop_endif
 #undef PTE_MAYBE_SHARED
 
 	orr	tcr2, tcr2, TCR2_EL1_PIE
-	msr	REG_TCR2_EL1, x0
 
 .Lskip_indirection:
 
-- 
2.39.5