From: Jim Mattson <jmattson@google.com>
To: linux-kernel@vger.kernel.org, x86@kernel.org
Cc: Jim Mattson <jmattson@google.com>,
Tavis Ormandy <taviso@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>, Kyle Huey <me@kylehuey.com>,
"Chang S. Bae" <chang.seok.bae@intel.com>,
Feng Tang <feng.tang@intel.com>,
Andrew Cooper <andrew.cooper3@citrix.com>
Subject: [PATCH] x86/fpu/xstate: Fix PKRU covert channel
Date: Wed, 30 Aug 2023 21:32:21 -0700 [thread overview]
Message-ID: <20230831043228.1194256-1-jmattson@google.com> (raw)
When XCR0[9] is set, PKRU can be read and written from userspace with
XSAVE and XRSTOR, even when CR4.PKE is clear.
Clear XCR0[9] when protection keys are disabled.
Reported-by: Tavis Ormandy <taviso@google.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
---
arch/x86/kernel/fpu/xstate.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 1afbc4866b10..a27b4f7b9365 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -71,7 +71,7 @@ static unsigned short xsave_cpuid_features[] __initdata = {
[XFEATURE_ZMM_Hi256] = X86_FEATURE_AVX512F,
[XFEATURE_Hi16_ZMM] = X86_FEATURE_AVX512F,
[XFEATURE_PT_UNIMPLEMENTED_SO_FAR] = X86_FEATURE_INTEL_PT,
- [XFEATURE_PKRU] = X86_FEATURE_PKU,
+ [XFEATURE_PKRU] = X86_FEATURE_OSPKE,
[XFEATURE_PASID] = X86_FEATURE_ENQCMD,
[XFEATURE_XTILE_CFG] = X86_FEATURE_AMX_TILE,
[XFEATURE_XTILE_DATA] = X86_FEATURE_AMX_TILE,
--
2.42.0.283.g2d96d420d3-goog
next reply other threads:[~2023-08-31 4:33 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-31 4:32 Jim Mattson [this message]
2023-08-31 19:12 ` Dave Hansen
2023-08-31 19:28 ` Jim Mattson
2023-08-31 21:36 ` [tip: x86/urgent] " tip-bot2 for Jim Mattson
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