linux-kernel - [PATCH for-4,5] mips/kvm: fix ioctl error handling

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Date:	Sun, 28 Feb 2016 17:35:59 +0200
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	stable@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
	James Hogan <james.hogan@...tec.com>,
	Ralf Baechle <ralf@...ux-mips.org>, kvm@...r.kernel.org,
	linux-mips@...ux-mips.org
Subject: [PATCH for-4,5] mips/kvm: fix ioctl error handling

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.

Cc: stable@...r.kernel.org
Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
---

Untested.

 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 8bc3977..3110447 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -702,7 +702,7 @@ 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;
 	}
@@ -732,7 +732,7 @@ 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;
 	}
-- 
MST