Patch "KVM: s390: avoid memory overwrites on emergency signal injection" has been added to the 4.1-stable tree

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 4.1-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-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: David Hildenbrand <[email protected]>
Date: Thu, 5 Nov 2015 09:38:15 +0100
Subject: KVM: s390: avoid memory overwrites on emergency signal injection

From: David Hildenbrand <[email protected]>

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.

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

@@ -1133,6 +1133,10 @@ static int __inject_sigp_emergency(struc
 	trace_kvm_s390_inject_vcpu(vcpu->vcpu_id, KVM_S390_INT_EMERGENCY,
 				   irq->u.emerg.code, 0, 2);
 
+	/* 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_set_mask(CPUSTAT_EXT_INT, li->cpuflags);

Patches currently in stable-queue which might be from [email protected] are

queue-4.1/kvm-s390-sca-must-not-cross-page-boundaries.patch queue-4.1/kvm-s390-fix-wrong-lookup-of-vcpus-by-array-index.patch queue-4.1/kvm-s390-avoid-memory-overwrites-on-emergency-signal-injection.patch