Patch "KVM: s390: avoid memory overwrites on emergency signal injection" has been added to the 4.3-stable tree

Patch "KVM: s390: avoid memory overwrites on emergency signal injection" has been added to the 4.3-stable tree

[gregkh]

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

    KVM: s390: avoid memory overwrites on emergency signal injection

to the 4.3-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-s390-avoid-memory-overwrites-on-emergency-signal-injection.patch
and it can be found in the queue-4.3 subdirectory.

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


>From b85de33a1a3433487b6a721cfdce25ec8673e622 Mon Sep 17 00:00:00 2001
From: David Hildenbrand <dahi@linux.vnet.ibm.com>
Date: Thu, 5 Nov 2015 09:38:15 +0100
Subject: KVM: s390: avoid memory overwrites on emergency signal injection

From: David Hildenbrand <dahi@linux.vnet.ibm.com>

commit b85de33a1a3433487b6a721cfdce25ec8673e622 upstream.

Commit 383d0b050106 ("KVM: s390: handle pending local interrupts via
bitmap") introduced a possible memory overwrite from user space.

User space could pass an invalid emergency signal code (sending VCPU)
and therefore exceed the bitmap. Let's take care of this case and
check that the id is in the valid range.

Reviewed-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/s390/kvm/interrupt.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -1136,6 +1136,10 @@ static int __inject_sigp_emergency(struc
 	trace_kvm_s390_inject_vcpu(vcpu->vcpu_id, KVM_S390_INT_EMERGENCY,
 				   irq->u.emerg.code, 0);
 
+	/* sending vcpu invalid */
+	if (kvm_get_vcpu_by_id(vcpu->kvm, irq->u.emerg.code) == NULL)
+		return -EINVAL;
+
 	set_bit(irq->u.emerg.code, li->sigp_emerg_pending);
 	set_bit(IRQ_PEND_EXT_EMERGENCY, &li->pending_irqs);
 	atomic_or(CPUSTAT_EXT_INT, li->cpuflags);


Patches currently in stable-queue which might be from dahi@linux.vnet.ibm.com are

queue-4.3/kvm-s390-sca-must-not-cross-page-boundaries.patch
queue-4.3/kvm-s390-enable-simd-only-when-no-vcpus-were-created.patch
queue-4.3/kvm-s390-fix-wrong-lookup-of-vcpus-by-array-index.patch
queue-4.3/kvm-s390-avoid-memory-overwrites-on-emergency-signal-injection.patch