linux-kernel - [added to the 4.1 stable tree] MIPS: kvm: Fix ioctl error handling.

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Date:	Sun, 13 Mar 2016 13:43:55 -0400
From:	Sasha Levin <sasha.levin@...cle.com>
To:	stable@...r.kernel.org, stable-commits@...r.kernel.org
Cc:	"Michael S. Tsirkin" <mst@...hat.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	James Hogan <james.hogan@...tec.com>,
	linux-kernel@...r.kernel.org, linux-mips@...ux-mips.org,
	kvm@...r.kernel.org, Ralf Baechle <ralf@...ux-mips.org>,
	Sasha Levin <sasha.levin@...cle.com>
Subject: [added to the 4.1 stable tree] MIPS: kvm: Fix ioctl error handling.

From: "Michael S. Tsirkin" <mst@...hat.com>

This patch has been added to the 4.1 stable tree. If you have any
objections, please let us know.

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

[ Upstream commit 887349f69f37e71e2a8bfbd743831625a0b2ff51 ]

Calling return copy_to_user(...) or return copy_from_user in an ioctl
will not do the right thing if there's a pagefault:
copy_to_user/copy_from_user return the number of bytes not copied in
this case.

Fix up kvm on mips to do
	return copy_to_user(...)) ?  -EFAULT : 0;
and
	return copy_from_user(...)) ?  -EFAULT : 0;

everywhere.

Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: James Hogan <james.hogan@...tec.com>
Cc: linux-kernel@...r.kernel.org
Cc: linux-mips@...ux-mips.org
Cc: stable@...r.kernel.org
Cc: kvm@...r.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/12709/
Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
---
 arch/mips/kvm/mips.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 22ee0af..ace4ed7 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -700,7 +700,7 @@ static int kvm_mips_get_reg(struct kvm_vcpu *vcpu,
 	} else if ((reg->id & KVM_REG_SIZE_MASK) == KVM_REG_SIZE_U128) {
 		void __user *uaddr = (void __user *)(long)reg->addr;
 
-		return copy_to_user(uaddr, vs, 16);
+		return copy_to_user(uaddr, vs, 16) ? -EFAULT : 0;
 	} else {
 		return -EINVAL;
 	}
@@ -730,7 +730,7 @@ static int kvm_mips_set_reg(struct kvm_vcpu *vcpu,
 	} else if ((reg->id & KVM_REG_SIZE_MASK) == KVM_REG_SIZE_U128) {
 		void __user *uaddr = (void __user *)(long)reg->addr;
 
-		return copy_from_user(vs, uaddr, 16);
+		return copy_from_user(vs, uaddr, 16) ? -EFAULT : 0;
 	} else {
 		return -EINVAL;
 	}
-- 
2.5.0