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[SRU,J/N,2/2] x86/sev: Check for MWAITX and MONITORX opcodes in the #VC handler

Message ID 20240703221157.1675604-4-yuxuan.luo@canonical.com
State New
Headers show
Series CVE-2024-25742 | expand

Commit Message

Yuxuan Luo July 3, 2024, 10:11 p.m. UTC 
From: Tom Lendacky <thomas.lendacky@amd.com>

The MWAITX and MONITORX instructions generate the same #VC error code as
the MWAIT and MONITOR instructions, respectively. Update the #VC handler
opcode checking to also support the MWAITX and MONITORX opcodes.

Fixes: e3ef461af35a ("x86/sev: Harden #VC instruction emulation somewhat")
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/453d5a7cfb4b9fe818b6fb67f93ae25468bc9e23.1713793161.git.thomas.lendacky@amd.com
(cherry picked from commit e70316d17f6ab49a6038ffd115397fd68f8c7be8)
CVE-2024-25742
Signed-off-by: Yuxuan Luo <yuxuan.luo@canonical.com>
---
 arch/x86/kernel/sev-shared.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
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Patch

diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c
index 263ee1f400b8d..d474197e33d4a 100644
--- a/arch/x86/kernel/sev-shared.c
+++ b/arch/x86/kernel/sev-shared.c
@@ -596,12 +596,14 @@  static enum es_result vc_check_opcode_bytes(struct es_em_ctxt *ctxt,
 		break;
 
 	case SVM_EXIT_MONITOR:
-		if (opcode == 0x010f && modrm == 0xc8)
+		/* MONITOR and MONITORX instructions generate the same error code */
+		if (opcode == 0x010f && (modrm == 0xc8 || modrm == 0xfa))
 			return ES_OK;
 		break;
 
 	case SVM_EXIT_MWAIT:
-		if (opcode == 0x010f && modrm == 0xc9)
+		/* MWAIT and MWAITX instructions generate the same error code */
+		if (opcode == 0x010f && (modrm == 0xc9 || modrm == 0xfb))
 			return ES_OK;
 		break;