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CVE-2014-3690 kvm: invalid host cr4 handling (rhbz 1153322 1155372)

This commit is contained in:
Josh Boyer 2014-10-22 12:45:05 -04:00
parent 56e56f3485
commit 5d44dc759a
2 changed files with 89 additions and 0 deletions
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8
kernel.spec
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@ -745,6 +745,9 @@ Patch26058: asus-nb-wmi-Add-wapf4-quirk-for-the-X550VB.patch
#rhbz 1153381
Patch26059: Input-synaptics-gate-forcepad-support-by-DMI-check.patch
# CVE-2014-3690 rhbz 1153322 1155372
Patch26060: x86-kvm-vmx-Preserve-CR4-across-VM-entry.patch
# git clone ssh://git.fedorahosted.org/git/kernel-arm64.git, git diff master...devel
Patch30000: kernel-arm64.patch
@ -1458,6 +1461,10 @@ ApplyPatch asus-nb-wmi-Add-wapf4-quirk-for-the-X550VB.patch
#rhbz 1153381
ApplyPatch Input-synaptics-gate-forcepad-support-by-DMI-check.patch
# CVE-2014-3690 rhbz 1153322 1155372
ApplyPatch x86-kvm-vmx-Preserve-CR4-across-VM-entry.patch
%if 0%{?aarch64patches}
ApplyPatch kernel-arm64.patch
%ifnarch aarch64 # this is stupid, but i want to notice before secondary koji does.
@ -2277,6 +2284,7 @@ fi
# || ||
%changelog
* Wed Oct 22 2014 Josh Boyer <jwboyer@fedoraproject.org>
- CVE-2014-3690 kvm: invalid host cr4 handling (rhbz 1153322 1155372)
- Add patch to fix synaptics forcepad issues (rhbz 1153381)
- Add patch to fix wifi on X550VB machines (rhbz 1089731)

81
x86-kvm-vmx-Preserve-CR4-across-VM-entry.patch Normal file
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@ -0,0 +1,81 @@
From: Andy Lutomirski <luto@amacapital.net>
Date: Wed, 8 Oct 2014 09:02:13 -0700
Subject: [PATCH] x86,kvm,vmx: Preserve CR4 across VM entry
CR4 isn't constant; at least the TSD and PCE bits can vary.
TBH, treating CR0 and CR3 as constant scares me a bit, too, but it looks
like it's correct.
This adds a branch and a read from cr4 to each vm entry. Because it is
extremely likely that consecutive entries into the same vcpu will have
the same host cr4 value, this fixes up the vmcs instead of restoring cr4
after the fact. A subsequent patch will add a kernel-wide cr4 shadow,
reducing the overhead in the common case to just two memory reads and a
branch.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: stable@vger.kernel.org
Cc: Petr Matousek <pmatouse@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
arch/x86/kvm/vmx.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index bfe11cf124a1..6a118fa378b5 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -453,6 +453,7 @@ struct vcpu_vmx {
int gs_ldt_reload_needed;
int fs_reload_needed;
u64 msr_host_bndcfgs;
+ unsigned long vmcs_host_cr4; /* May not match real cr4 */
} host_state;
struct {
int vm86_active;
@@ -4235,11 +4236,16 @@ static void vmx_set_constant_host_state(struct vcpu_vmx *vmx)
u32 low32, high32;
unsigned long tmpl;
struct desc_ptr dt;
+ unsigned long cr4;
vmcs_writel(HOST_CR0, read_cr0() & ~X86_CR0_TS); /* 22.2.3 */
- vmcs_writel(HOST_CR4, read_cr4()); /* 22.2.3, 22.2.5 */
vmcs_writel(HOST_CR3, read_cr3()); /* 22.2.3 FIXME: shadow tables */
+ /* Save the most likely value for this task's CR4 in the VMCS. */
+ cr4 = read_cr4();
+ vmcs_writel(HOST_CR4, cr4); /* 22.2.3, 22.2.5 */
+ vmx->host_state.vmcs_host_cr4 = cr4;
+
vmcs_write16(HOST_CS_SELECTOR, __KERNEL_CS); /* 22.2.4 */
#ifdef CONFIG_X86_64
/*
@@ -7376,7 +7382,7 @@ static void atomic_switch_perf_msrs(struct vcpu_vmx *vmx)
static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
- unsigned long debugctlmsr;
+ unsigned long debugctlmsr, cr4;
/* Record the guest's net vcpu time for enforced NMI injections. */
if (unlikely(!cpu_has_virtual_nmis() && vmx->soft_vnmi_blocked))
@@ -7397,6 +7403,12 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
if (test_bit(VCPU_REGS_RIP, (unsigned long *)&vcpu->arch.regs_dirty))
vmcs_writel(GUEST_RIP, vcpu->arch.regs[VCPU_REGS_RIP]);
+ cr4 = read_cr4();
+ if (unlikely(cr4 != vmx->host_state.vmcs_host_cr4)) {
+ vmcs_writel(HOST_CR4, cr4);
+ vmx->host_state.vmcs_host_cr4 = cr4;
+ }
+
/* When single-stepping over STI and MOV SS, we must clear the
* corresponding interruptibility bits in the guest state. Otherwise
* vmentry fails as it then expects bit 14 (BS) in pending debug
--
1.9.3