linux-kernel - [PATCH 1/3] x86/execmem: don't use PAGE

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Message-ID: <20250528123557.12847-2-jgross@suse.com>
Date: Wed, 28 May 2025 14:35:55 +0200
From: Juergen Gross <jgross@...e.com>
To: linux-kernel@...r.kernel.org,
	x86@...nel.org
Cc: xin@...or.com,
	Juergen Gross <jgross@...e.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Andy Lutomirski <luto@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	stable@...r.kernel.org
Subject: [PATCH 1/3] x86/execmem: don't use PAGE_KERNEL protection for code pages

In case X86_FEATURE_PSE isn't available (e.g. when running as a Xen
PV guest), execmem_arch_setup() will fall back to use PAGE_KERNEL
protection for the EXECMEM_MODULE_TEXT range.

This will result in attempts to execute code with the NX bit set in
case of ITS mitigation being applied.

Avoid this problem by using PAGE_KERNEL_EXEC protection instead,
which will not set the NX bit.

Cc: <stable@...r.kernel.org>
Reported-by: Xin Li <xin@...or.com>
Fixes: 5185e7f9f3bd ("x86/module: enable ROX caches for module text on 64 bit")
Signed-off-by: Juergen Gross <jgross@...e.com>
---
 arch/x86/mm/init.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 7456df985d96..f5012ae31d8b 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -1089,7 +1089,7 @@ struct execmem_info __init *execmem_arch_setup(void)
 		pgprot = PAGE_KERNEL_ROX;
 		flags = EXECMEM_KASAN_SHADOW | EXECMEM_ROX_CACHE;
 	} else {
-		pgprot = PAGE_KERNEL;
+		pgprot = PAGE_KERNEL_EXEC;
 		flags = EXECMEM_KASAN_SHADOW;
 	}
 
-- 
2.43.0