Re: [PATCH] x86/kvm/vmx: Fix GPF on reading vmentry_l1d_flush

From: MINOURA Makoto / 箕浦 真 <redacted>
Date: 2018年8月22日周三 上午9:50
Subject: [PATCH] x86/kvm/vmx: Fix GPF on reading vmentry_l1d_flush
To: <redacted>
Cc: <redacted>



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 <redacted>
---
 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;
                }