Patch "KVM: s390: reinjection of irqs can fail in the tpi handler" has been added to the 4.0-stable tree

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

KVM: s390: reinjection of irqs can fail in the tpi handler

to the 4.0-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-reinjection-of-irqs-can-fail-in-the-tpi-handler.patch
and it can be found in the queue-4.0 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: Wed, 4 Feb 2015 15:59:11 +0100
Subject: KVM: s390: reinjection of irqs can fail in the tpi handler

From: David Hildenbrand <[email protected]>

commit 15462e37ca848abac7477dece65f8af25febd744 upstream.

The reinjection of an I/O interrupt can fail if the list is at the limit and between the dequeue and the reinjection, another I/O interrupt is injected (e.g. if user space floods kvm with I/O interrupts).

This patch avoids this memory leak and returns -EFAULT in this special case. This error is not recoverable, so let's fail hard. This can later be avoided by not dequeuing the interrupt but working directly on the locked list.

---
 arch/s390/kvm/interrupt.c |    4 ++--
 arch/s390/kvm/kvm-s390.h  |    4 ++--
 arch/s390/kvm/priv.c      |    5 ++++-
 3 files changed, 8 insertions(+), 5 deletions(-)

@@ -1332,10 +1332,10 @@ int kvm_s390_inject_vm(struct kvm *kvm,
 	return rc;
 }
 
-void kvm_s390_reinject_io_int(struct kvm *kvm,
+int kvm_s390_reinject_io_int(struct kvm *kvm,
 			      struct kvm_s390_interrupt_info *inti)
 {
-	__inject_vm(kvm, inti);
+	return __inject_vm(kvm, inti);
 }
 
 int s390int_to_s390irq(struct kvm_s390_interrupt *s390int,

@@ -151,8 +151,8 @@ int __must_check kvm_s390_inject_vcpu(st
 int __must_check kvm_s390_inject_program_int(struct kvm_vcpu *vcpu, u16 code);
 struct kvm_s390_interrupt_info *kvm_s390_get_io_int(struct kvm *kvm,
 						    u64 cr6, u64 schid);
-void kvm_s390_reinject_io_int(struct kvm *kvm,
-			      struct kvm_s390_interrupt_info *inti);
+int kvm_s390_reinject_io_int(struct kvm *kvm,
+			     struct kvm_s390_interrupt_info *inti);
 int kvm_s390_mask_adapter(struct kvm *kvm, unsigned int id, bool masked);
 
 /* implemented in intercept.c */

@@ -279,7 +279,10 @@ reinject_interrupt:
 	 * instruction is suppressed from the guest's view: reinject the
 	 * interrupt.
 	 */
-	kvm_s390_reinject_io_int(vcpu->kvm, inti);
+	if (kvm_s390_reinject_io_int(vcpu->kvm, inti)) {
+		kfree(inti);
+		rc = -EFAULT;
+	}
 	/* don't set the cc, a pgm irq was injected or we drop to user space */
 	return rc ? -EFAULT : 0;
 }

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

queue-4.0/kvm-s390-zero-out-current-vmdb-of-stsi-before-including-level3-data.patch queue-4.0/kvm-s390-reinjection-of-irqs-can-fail-in-the-tpi-handler.patch queue-4.0/kvm-s390-fix-get_all_floating_irqs.patch queue-4.0/kvm-s390-fix-handling-of-write-errors-in-the-tpi-handler.patch