Commit fb1b32a3 authored by Salvatore Bonaccorso's avatar Salvatore Bonaccorso

[x86] KVM: work around leak of uninitialized stack contents (CVE-2019-7222)

parent 71aa687b
......@@ -393,6 +393,8 @@ linux (4.19.20-1) UNRELEASED; urgency=medium
[ Salvatore Bonaccorso ]
* [x86] kvmclock: set offset for kvm unstable clock (Closes: #918036)
* kvm: fix kvm_ioctl_create_device() reference counting (CVE-2019-6974)
* [x86] KVM: work around leak of uninitialized stack contents
(CVE-2019-7222)
[ Hideki Yamane ]
* [x86] Enable Touchpad support on Gemini Lake via CONFIG_PINCTRL_GEMINILAKE
......
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Tue, 29 Jan 2019 18:41:16 +0100
Subject: KVM: x86: work around leak of uninitialized stack contents
(CVE-2019-7222)
Origin: https://git.kernel.org/linus/353c0956a618a07ba4bbe7ad00ff29fe70e8412a
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2019-7222
Bugzilla: 1671930
Emulation of certain instructions (VMXON, VMCLEAR, VMPTRLD, VMWRITE with
memory operand, INVEPT, INVVPID) can incorrectly inject a page fault
when passed an operand that points to an MMIO address. The page fault
will use uninitialized kernel stack memory as the CR2 and error code.
The right behavior would be to abort the VM with a KVM_EXIT_INTERNAL_ERROR
exit to userspace; however, it is not an easy fix, so for now just
ensure that the error code and CR2 are zero.
Embargoed until Feb 7th 2019.
Reported-by: Felix Wilhelm <fwilhelm@google.com>
Cc: stable@kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/x86.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 3d27206f6c01..e67ecf25e690 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5116,6 +5116,13 @@ int kvm_read_guest_virt(struct kvm_vcpu *vcpu,
{
u32 access = (kvm_x86_ops->get_cpl(vcpu) == 3) ? PFERR_USER_MASK : 0;
+ /*
+ * FIXME: this should call handle_emulation_failure if X86EMUL_IO_NEEDED
+ * is returned, but our callers are not ready for that and they blindly
+ * call kvm_inject_page_fault. Ensure that they at least do not leak
+ * uninitialized kernel stack memory into cr2 and error code.
+ */
+ memset(exception, 0, sizeof(*exception));
return kvm_read_guest_virt_helper(addr, val, bytes, vcpu, access,
exception);
}
--
2.11.0
......@@ -140,6 +140,7 @@ features/all/lockdown/arm64-add-kernel-config-option-to-lock-down-when.patch
# Security fixes
debian/i386-686-pae-pci-set-pci-nobios-by-default.patch
bugfix/all/kvm-fix-kvm_ioctl_create_device-reference-counting-C.patch
bugfix/x86/KVM-x86-work-around-leak-of-uninitialized-stack-cont.patch
# Fix exported symbol versions
bugfix/all/module-disable-matching-missing-version-crc.patch
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment