linux-kernel - [PATCH v2] x86/mtrr: Check if fixed-range MTRR exists in mtrr_save_fixed

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-next>] [day] [month] [year] [list]

Message-ID: <20250509170633.3411169-2-jiaqing.zhao@linux.intel.com>
Date: Fri,  9 May 2025 17:06:33 +0000
From: Jiaqing Zhao <jiaqing.zhao@...ux.intel.com>
To: Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Bernhard Kaindl <bk@...e.de>,
	Andi Kleen <ak@...ux.intel.com>
Cc: Li Fei <fei1.li@...el.com>,
	Jiaqing Zhao <jiaqing.zhao@...ux.intel.com>,
	stable@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2] x86/mtrr: Check if fixed-range MTRR exists in mtrr_save_fixed_ranges()

When suspending, save_processor_state() calls mtrr_save_fixed_ranges()
to save fixed-range MTRRs. On platforms without fixed-range MTRRs,
accessing these MSRs will trigger unchecked MSR access error. Make
sure fixed-range MTRRs are supported before access to prevent such
error.

Since mtrr_state.have_fixed is only set when MTRRs are present and
enabled, checking the CPU feature flag in mtrr_save_fixed_ranges()
is unnecessary.

Fixes: 3ebad5905609 ("[PATCH] x86: Save and restore the fixed-range MTRRs of the BSP when suspending")
Cc: stable@...r.kernel.org
Signed-off-by: Jiaqing Zhao <jiaqing.zhao@...ux.intel.com>
---
v2:
* Removed unnecessary boot_cpu_has(X86_FEATURE_MTRR) check.
* Updated commit message.
Link: https://lore.kernel.org/all/20250509085612.2236222-2-jiaqing.zhao@linux.intel.com

 arch/x86/kernel/cpu/mtrr/generic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index e2c6b471d230..8c18327eb10b 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -593,7 +593,7 @@ static void get_fixed_ranges(mtrr_type *frs)
 
 void mtrr_save_fixed_ranges(void *info)
 {
-	if (boot_cpu_has(X86_FEATURE_MTRR))
+	if (mtrr_state.have_fixed)
 		get_fixed_ranges(mtrr_state.fixed_ranges);
 }
 
-- 
2.43.0