Patch "KVM: x86: fix for buffer overflow in handling of MSR_KVM_SYSTEM_TIME (CVE-2013-1796)" has been added to the 3.8-stable tree

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



This is a note to let you know that I've just added the patch titled

    KVM: x86: fix for buffer overflow in handling of MSR_KVM_SYSTEM_TIME (CVE-2013-1796)

to the 3.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kvm-x86-fix-for-buffer-overflow-in-handling-of-msr_kvm_system_time-cve-2013-1796.patch
and it can be found in the queue-3.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From c300aa64ddf57d9c5d9c898a64b36877345dd4a9 Mon Sep 17 00:00:00 2001
From: Andy Honig <ahonig@xxxxxxxxxx>
Date: Mon, 11 Mar 2013 09:34:52 -0700
Subject: KVM: x86: fix for buffer overflow in handling of MSR_KVM_SYSTEM_TIME (CVE-2013-1796)

From: Andy Honig <ahonig@xxxxxxxxxx>

commit c300aa64ddf57d9c5d9c898a64b36877345dd4a9 upstream.

If the guest sets the GPA of the time_page so that the request to update the
time straddles a page then KVM will write onto an incorrect page.  The
write is done byusing kmap atomic to get a pointer to the page for the time
structure and then performing a memcpy to that page starting at an offset
that the guest controls.  Well behaved guests always provide a 32-byte aligned
address, however a malicious guest could use this to corrupt host kernel
memory.

Tested: Tested against kvmclock unit test.

Signed-off-by: Andrew Honig <ahonig@xxxxxxxxxx>
Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Cc: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/x86/kvm/x86.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1960,6 +1960,11 @@ int kvm_set_msr_common(struct kvm_vcpu *
 		/* ...but clean it before doing the actual write */
 		vcpu->arch.time_offset = data & ~(PAGE_MASK | 1);
 
+		/* Check that the address is 32-byte aligned. */
+		if (vcpu->arch.time_offset &
+				(sizeof(struct pvclock_vcpu_time_info) - 1))
+			break;
+
 		vcpu->arch.time_page =
 				gfn_to_page(vcpu->kvm, data >> PAGE_SHIFT);
 


Patches currently in stable-queue which might be from ahonig@xxxxxxxxxx are

queue-3.8/kvm-allow-cross-page-reads-and-writes-from-cached-translations.patch
queue-3.8/kvm-fix-bounds-checking-in-ioapic-indirect-register-reads-cve-2013-1798.patch
queue-3.8/kvm-x86-convert-msr_kvm_system_time-to-use-gfn_to_hva_cache-functions-cve-2013-1797.patch
queue-3.8/kvm-x86-fix-for-buffer-overflow-in-handling-of-msr_kvm_system_time-cve-2013-1796.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]