[PATCH] KVM: x86: Fix KVM_GET_MSR_INDEX_LIST

From: Jan Kiszka <jan.kiszka@web.de>
To: Avi Kivity <avi@redhat.com>
Cc: kvm-devel <kvm@vger.kernel.org>
Subject: [PATCH] KVM: x86: Fix KVM_GET_MSR_INDEX_LIST
Date: Thu, 02 Jul 2009 21:45:47 +0200	[thread overview]
Message-ID: <4A4D0E6B.6090105@web.de> (raw)

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So far, KVM copied the emulated_msrs (only MSR_IA32_MISC_ENABLE) to a
wrong address in user space due to broken pointer arithmetic. This
caused subtle corruption up there (missing MSR_IA32_MISC_ENABLE had
probably no practical relevance). Moreover, the size check for the
user-provided kvm_msr_list forgot about emulated MSRs.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---

 arch/x86/kvm/x86.c |    5 ++---
 1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 26dde25..1ed62a1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1252,14 +1252,13 @@ long kvm_arch_dev_ioctl(struct file *filp,
 		if (copy_to_user(user_msr_list, &msr_list, sizeof msr_list))
 			goto out;
 		r = -E2BIG;
-		if (n < num_msrs_to_save)
+		if (n < msr_list.nmsrs)
 			goto out;
 		r = -EFAULT;
 		if (copy_to_user(user_msr_list->indices, &msrs_to_save,
 				 num_msrs_to_save * sizeof(u32)))
 			goto out;
-		if (copy_to_user(user_msr_list->indices
-				 + num_msrs_to_save * sizeof(u32),
+		if (copy_to_user(user_msr_list->indices + num_msrs_to_save,
 				 &emulated_msrs,
 				 ARRAY_SIZE(emulated_msrs) * sizeof(u32)))
 			goto out;


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