linux-kernel - [PATCH] x86/kvm/vmx: Fix GPF on reading vmentry_l1d

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Message-ID: <kk5mute6dt2.fsf@brer.local.valinux.co.jp>
Date:   Wed, 22 Aug 2018 16:49:45 +0900
From:   MINOURA Makoto / 箕浦 真 
        <minoura@...inux.co.jp>
To:     kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH] x86/kvm/vmx: Fix GPF on reading vmentry_l1d_flush


When EPT is not enabled, reading
/sys/module/kvm_intel/parameters/vmentry_l1d_flush causes
general protection fault in vmentry_l1d_flush_get() due to
access beyond the end of the array vmentry_l1d_param[].

Signed-off-by: Minoura Makoto <minoura@...inux.co.jp>
---
 arch/x86/include/asm/vmx.h | 1 +
 arch/x86/kvm/vmx.c         | 4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 95f9107449bf..c4b834b05178 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -581,6 +581,7 @@ enum vmx_l1d_flush_state {
 	VMENTER_L1D_FLUSH_NEVER,
 	VMENTER_L1D_FLUSH_COND,
 	VMENTER_L1D_FLUSH_ALWAYS,
+	VMENTER_L1D_FLUSH_PARAM_MAX = VMENTER_L1D_FLUSH_ALWAYS,
 	VMENTER_L1D_FLUSH_EPT_DISABLED,
 	VMENTER_L1D_FLUSH_NOT_REQUIRED,
 };
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 1519f030fd73..155ba2a9139f 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -204,6 +204,8 @@ static const struct {
 	{"never",	VMENTER_L1D_FLUSH_NEVER},
 	{"cond",	VMENTER_L1D_FLUSH_COND},
 	{"always",	VMENTER_L1D_FLUSH_ALWAYS},
+	{"ept-disabled", VMENTER_L1D_FLUSH_EPT_DISABLED},
+	{"not-required", VMENTER_L1D_FLUSH_NOT_REQUIRED},
 };
 
 #define L1D_CACHE_ORDER 4
@@ -286,7 +288,7 @@ static int vmentry_l1d_flush_parse(const char *s)
 	unsigned int i;
 
 	if (s) {
-		for (i = 0; i < ARRAY_SIZE(vmentry_l1d_param); i++) {
+		for (i = 0; i <= VMENTER_L1D_FLUSH_PARAM_MAX; i++) {
 			if (sysfs_streq(s, vmentry_l1d_param[i].option))
 				return vmentry_l1d_param[i].cmd;
 		}