linux-kernel - [PATCH 3.12 10/84] arm64: KVM: Fix host crash when injecting a fault into a 32bit guest

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Message-Id: <a246a015d49f0a6133c255cd9ce688f3342b51ae.1443792303.git.jslaby@suse.cz>
Date:	Fri,  2 Oct 2015 15:24:15 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Marc Zyngier <marc.zyngier@....com>,
	Will Deacon <will.deacon@....com>, Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 10/84] arm64: KVM: Fix host crash when injecting a fault into a 32bit guest

From: Marc Zyngier <marc.zyngier@....com>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 126c69a0bd0e441bf6766a5d9bf20de011be9f68 upstream.

When injecting a fault into a misbehaving 32bit guest, it seems
rather idiotic to also inject a 64bit fault that is only going
to corrupt the guest state. This leads to a situation where we
perform an illegal exception return at EL2 causing the host
to crash instead of killing the guest.

Just fix the stupid bug that has been there from day 1.

Reported-by: Russell King <rmk+kernel@....linux.org.uk>
Tested-by: Russell King <rmk+kernel@....linux.org.uk>
Signed-off-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 arch/arm64/kvm/inject_fault.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/kvm/inject_fault.c b/arch/arm64/kvm/inject_fault.c
index 81a02a8762b0..86825f8883de 100644
--- a/arch/arm64/kvm/inject_fault.c
+++ b/arch/arm64/kvm/inject_fault.c
@@ -168,8 +168,8 @@ void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr)
 {
 	if (!(vcpu->arch.hcr_el2 & HCR_RW))
 		inject_abt32(vcpu, false, addr);
-
-	inject_abt64(vcpu, false, addr);
+	else
+		inject_abt64(vcpu, false, addr);
 }
 
 /**
@@ -184,8 +184,8 @@ void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr)
 {
 	if (!(vcpu->arch.hcr_el2 & HCR_RW))
 		inject_abt32(vcpu, true, addr);
-
-	inject_abt64(vcpu, true, addr);
+	else
+		inject_abt64(vcpu, true, addr);
 }
 
 /**
@@ -198,6 +198,6 @@ void kvm_inject_undefined(struct kvm_vcpu *vcpu)
 {
 	if (!(vcpu->arch.hcr_el2 & HCR_RW))
 		inject_undef32(vcpu);
-
-	inject_undef64(vcpu);
+	else
+		inject_undef64(vcpu);
 }
-- 
2.6.0

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