Skip to contentSkip to conversation

Patch "KVM: arm/arm64: vgic: Fix deadlock on error handling" has been added to the 4.9-stable tree

PATCH [email protected] 1 participant 1 message Jan 23, 2017 Stable branch

lore
Share & tools
lore

[email protected]

author maintainer Applied
#0 lore raw

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

KVM: arm/arm64: vgic: Fix deadlock on error handling

to the 4.9-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-arm-arm64-vgic-fix-deadlock-on-error-handling.patch
and it can be found in the queue-4.9 subdirectory.

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

Quoted 1 line

From 1193e6aeecb36c74c48c7cd0f641acbbed9ddeef Mon Sep 17 00:00:00 2001

From: Marc Zyngier <[email protected]>
Date: Thu, 12 Jan 2017 09:21:56 +0000
Subject: KVM: arm/arm64: vgic: Fix deadlock on error handling

From: Marc Zyngier <[email protected]>

commit 1193e6aeecb36c74c48c7cd0f641acbbed9ddeef upstream.

Dmitry Vyukov reported that the syzkaller fuzzer triggered a deadlock in the vgic setup code when an error was detected, as the cleanup code tries to take a lock that is already held by the setup code.

The fix is to avoid retaking the lock when cleaning up, by telling the cleanup function that we already hold it.

Reported-by Dmitry Vyukov <[email protected]>
Reviewed-by Christoffer Dall <[email protected]>
Reviewed-by Eric Auger <[email protected]>
Signed-off-by Marc Zyngier <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 virt/kvm/arm/vgic/vgic-init.c |   18 +++++++++++++-----
 virt/kvm/arm/vgic/vgic-v2.c   |    2 --
 virt/kvm/arm/vgic/vgic-v3.c   |    2 --
 3 files changed, 13 insertions(+), 9 deletions(-)
virt/kvm/arm/vgic/vgic-init.c +13 -5
@@ -268,15 +268,11 @@ static void kvm_vgic_dist_destroy(struct
 {
 	struct vgic_dist *dist = &kvm->arch.vgic;
 
-	mutex_lock(&kvm->lock);
-
 	dist->ready = false;
 	dist->initialized = false;
 
 	kfree(dist->spis);
 	dist->nr_spis = 0;
-
-	mutex_unlock(&kvm->lock);
 }
 
 void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)

@@ -286,7 +282,8 @@ void kvm_vgic_vcpu_destroy(struct kvm_vc
 	INIT_LIST_HEAD(&vgic_cpu->ap_list_head);
 }
 
-void kvm_vgic_destroy(struct kvm *kvm)
+/* To be called with kvm->lock held */
+static void __kvm_vgic_destroy(struct kvm *kvm)
 {
 	struct kvm_vcpu *vcpu;
 	int i;

@@ -297,6 +294,13 @@ void kvm_vgic_destroy(struct kvm *kvm)
 		kvm_vgic_vcpu_destroy(vcpu);
 }
 
+void kvm_vgic_destroy(struct kvm *kvm)
+{
+	mutex_lock(&kvm->lock);
+	__kvm_vgic_destroy(kvm);
+	mutex_unlock(&kvm->lock);
+}
+
 /**
  * vgic_lazy_init: Lazy init is only allowed if the GIC exposed to the guest
  * is a GICv2. A GICv3 must be explicitly initialized by the guest using the

@@ -348,6 +352,10 @@ int kvm_vgic_map_resources(struct kvm *k
 		ret = vgic_v2_map_resources(kvm);
 	else
 		ret = vgic_v3_map_resources(kvm);
+
+	if (ret)
+		__kvm_vgic_destroy(kvm);
+
 out:
 	mutex_unlock(&kvm->lock);
 	return ret;
virt/kvm/arm/vgic/vgic-v2.c +0 -2
@@ -293,8 +293,6 @@ int vgic_v2_map_resources(struct kvm *kv
 	dist->ready = true;
 
 out:
-	if (ret)
-		kvm_vgic_destroy(kvm);
 	return ret;
 }
virt/kvm/arm/vgic/vgic-v3.c +0 -2
@@ -302,8 +302,6 @@ int vgic_v3_map_resources(struct kvm *kv
 	dist->ready = true;
 
 out:
-	if (ret)
-		kvm_vgic_destroy(kvm);
 	return ret;
 }

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

queue-4.9/kvm-arm-arm64-vgic-fix-deadlock-on-error-handling.patch