linux-kernel - [PATCH stable <3.17] MIPS: KVM: Do not sign extend on unsigned MMIO load

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Date:	Wed, 8 Jul 2015 15:25:07 +0100
From:	James Hogan <james.hogan@...tec.com>
To:	Greg KH <greg@...ah.com>
CC:	Nicholas Mc Guire <hofrat@...dl.org>,
	Gleb Natapov <gleb@...nel.org>,
	Paolo Bonzini <pbonzini@...hat.com>, <kvm@...r.kernel.org>,
	<linux-mips@...ux-mips.org>, <linux-kernel@...r.kernel.org>,
	Ralf Baechle <ralf@...ux-mips.org>, <stable@...r.kernel.org>,
	James Hogan <james.hogan@...tec.com>
Subject: [PATCH stable <3.17] MIPS: KVM: Do not sign extend on unsigned MMIO load

From: Nicholas Mc Guire <hofrat@...dl.org>

commit ed9244e6c534612d2b5ae47feab2f55a0d4b4ced upstream.

Fix possible unintended sign extension in unsigned MMIO loads by casting
to uint16_t in the case of mmio_needed != 2.

Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
Reviewed-by: James Hogan <james.hogan@...tec.com>
Tested-by: James Hogan <james.hogan@...tec.com>
Cc: Gleb Natapov <gleb@...nel.org>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org
Cc: linux-mips@...ux-mips.org
Cc: linux-kernel@...r.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/9985/
Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
Cc: <stable@...r.kernel.org> # v3.10+
Signed-off-by: James Hogan <james.hogan@...tec.com>
---
This is a trivial backport (i.e. git cherry-pick, git format-patch) for
stable branches before v3.17, due to the commit d7d5b05faf16 ("MIPS:
KVM: Rename files to remove the prefix "kvm_" and "kvm_mips_"") which
renamed a bunch of files including this one.
---
 arch/mips/kvm/kvm_mips_emul.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/mips/kvm/kvm_mips_emul.c b/arch/mips/kvm/kvm_mips_emul.c
index e75ef8219caf..c76f297b7149 100644
--- a/arch/mips/kvm/kvm_mips_emul.c
+++ b/arch/mips/kvm/kvm_mips_emul.c
@@ -1626,7 +1626,7 @@ kvm_mips_complete_mmio_load(struct kvm_vcpu *vcpu, struct kvm_run *run)
 		if (vcpu->mmio_needed == 2)
 			*gpr = *(int16_t *) run->mmio.data;
 		else
-			*gpr = *(int16_t *) run->mmio.data;
+			*gpr = *(uint16_t *)run->mmio.data;
 
 		break;
 	case 1:
-- 
2.3.6

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