lkml.org 
[lkml]   [2014]   [Nov]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 3.13 098/162] KVM: x86: Improve thread safety in pit
Date
3.13.11.11 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Honig <ahonig@google.com>

commit 2febc839133280d5a5e8e1179c94ea674489dae2 upstream.

There's a race condition in the PIT emulation code in KVM. In
__kvm_migrate_pit_timer the pit_timer object is accessed without
synchronization. If the race condition occurs at the wrong time this
can crash the host kernel.

This fixes CVE-2014-3611.

Signed-off-by: Andrew Honig <ahonig@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
arch/x86/kvm/i8254.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 518d864..298781d 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -262,8 +262,10 @@ void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu)
return;

timer = &pit->pit_state.timer;
+ mutex_lock(&pit->pit_state.lock);
if (hrtimer_cancel(timer))
hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
+ mutex_unlock(&pit->pit_state.lock);
}

static void destroy_pit_timer(struct kvm_pit *pit)
--
1.9.1


\
 
 \ /
  Last update: 2014-11-07 00:21    [W:0.496 / U:1.100 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site