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[arm64] KVM: Sanitize PSTATE.M when being set from userspace (CVE-2018-18021)

This commit is contained in:
Salvatore Bonaccorso 2018-10-07 08:33:57 +02:00
parent 20bad055e2
commit 2db297e8f5
3 changed files with 61 additions and 0 deletions
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2
debian/changelog vendored
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@ -6,6 +6,8 @@ linux (4.18.10-2) UNRELEASED; urgency=medium
[ Salvatore Bonaccorso ]
* [arm64] KVM: Tighten guest core register access from userspace
(CVE-2018-18021)
* [arm64] KVM: Sanitize PSTATE.M when being set from userspace
(CVE-2018-18021)
-- Ben Hutchings <ben@decadent.org.uk> Fri, 05 Oct 2018 18:09:26 +0100

58
debian/patches/bugfix/arm64/arm64-kvm-sanitize-pstate.m-when-being-set-from-user.patch vendored Normal file
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@ -0,0 +1,58 @@
From: Marc Zyngier <marc.zyngier@arm.com>
Date: Thu, 27 Sep 2018 16:53:22 +0100
Subject: arm64: KVM: Sanitize PSTATE.M when being set from userspace
Origin: https://git.kernel.org/linus/2a3f93459d689d990b3ecfbe782fec89b97d3279
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2018-18021
Not all execution modes are valid for a guest, and some of them
depend on what the HW actually supports. Let's verify that what
userspace provides is compatible with both the VM settings and
the HW capabilities.
Cc: <stable@vger.kernel.org>
Fixes: 0d854a60b1d7 ("arm64: KVM: enable initialization of a 32bit vcpu")
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
[carnil: Backport for 4.18: Cherrypick directly commit from 4.18.12 /
926415e1e4c9]
---
arch/arm64/kvm/guest.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 4a177629862b..d5c6bb1562d8 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -152,17 +152,25 @@ static int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
}
if (off == KVM_REG_ARM_CORE_REG(regs.pstate)) {
- u32 mode = (*(u32 *)valp) & COMPAT_PSR_MODE_MASK;
+ u64 mode = (*(u64 *)valp) & COMPAT_PSR_MODE_MASK;
switch (mode) {
case COMPAT_PSR_MODE_USR:
+ if (!system_supports_32bit_el0())
+ return -EINVAL;
+ break;
case COMPAT_PSR_MODE_FIQ:
case COMPAT_PSR_MODE_IRQ:
case COMPAT_PSR_MODE_SVC:
case COMPAT_PSR_MODE_ABT:
case COMPAT_PSR_MODE_UND:
+ if (!vcpu_el1_is_32bit(vcpu))
+ return -EINVAL;
+ break;
case PSR_MODE_EL0t:
case PSR_MODE_EL1t:
case PSR_MODE_EL1h:
+ if (vcpu_el1_is_32bit(vcpu))
+ return -EINVAL;
break;
default:
err = -EINVAL;
--
2.11.0

1
debian/patches/series vendored
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@ -146,6 +146,7 @@ bugfix/all/floppy-Do-not-copy-a-kernel-pointer-to-user-memory-i.patch
bugfix/all/scsi-target-iscsi-Use-hex2bin-instead-of-a-re-implem.patch
bugfix/all/scsi-target-iscsi-Use-bin2hex-instead-of-a-re-implem.patch
bugfix/arm64/arm64-kvm-tighten-guest-core-register-access-from-us.patch
bugfix/arm64/arm64-kvm-sanitize-pstate.m-when-being-set-from-user.patch
# Fix exported symbol versions
bugfix/all/module-disable-matching-missing-version-crc.patch