diff options
authorZenghui Yu <yuzenghui@huawei.com>2020-04-14 11:03:47 +0800
committerMarc Zyngier <maz@kernel.org>2020-04-23 16:26:56 +0100
commit969ce8b5260d8ec01e6f1949d2927a86419663ce (patch)
parentba1ed9e17b581c9a204ec1d72d40472dd8557edd (diff)
KVM: arm64: vgic-v3: Retire all pending LPIs on vcpu destroy
It's likely that the vcpu fails to handle all virtual interrupts if userspace decides to destroy it, leaving the pending ones stay in the ap_list. If the un-handled one is a LPI, its vgic_irq structure will be eventually leaked because of an extra refcount increment in vgic_queue_irq_unlock(). This was detected by kmemleak on almost every guest destroy, the backtrace is as follows: unreferenced object 0xffff80725aed5500 (size 128): comm "CPU 5/KVM", pid 40711, jiffies 4298024754 (age 166366.512s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 08 01 a9 73 6d 80 ff ff ...........sm... c8 61 ee a9 00 20 ff ff 28 1e 55 81 6c 80 ff ff .a... ..(.U.l... backtrace: [<000000004bcaa122>] kmem_cache_alloc_trace+0x2dc/0x418 [<0000000069c7dabb>] vgic_add_lpi+0x88/0x418 [<00000000bfefd5c5>] vgic_its_cmd_handle_mapi+0x4dc/0x588 [<00000000cf993975>] vgic_its_process_commands.part.5+0x484/0x1198 [<000000004bd3f8e3>] vgic_its_process_commands+0x50/0x80 [<00000000b9a65b2b>] vgic_mmio_write_its_cwriter+0xac/0x108 [<0000000009641ebb>] dispatch_mmio_write+0xd0/0x188 [<000000008f79d288>] __kvm_io_bus_write+0x134/0x240 [<00000000882f39ac>] kvm_io_bus_write+0xe0/0x150 [<0000000078197602>] io_mem_abort+0x484/0x7b8 [<0000000060954e3c>] kvm_handle_guest_abort+0x4cc/0xa58 [<00000000e0d0cd65>] handle_exit+0x24c/0x770 [<00000000b44a7fad>] kvm_arch_vcpu_ioctl_run+0x460/0x1988 [<0000000025fb897c>] kvm_vcpu_ioctl+0x4f8/0xee0 [<000000003271e317>] do_vfs_ioctl+0x160/0xcd8 [<00000000e7f39607>] ksys_ioctl+0x98/0xd8 Fix it by retiring all pending LPIs in the ap_list on the destroy path. p.s. I can also reproduce it on a normal guest shutdown. It is because userspace still send LPIs to vcpu (through KVM_SIGNAL_MSI ioctl) while the guest is being shutdown and unable to handle it. A little strange though and haven't dig further... Reviewed-by: James Morse <james.morse@arm.com> Signed-off-by: Zenghui Yu <yuzenghui@huawei.com> [maz: moved the distributor deallocation down to avoid an UAF splat] Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20200414030349.625-2-yuzenghui@huawei.com
1 files changed, 8 insertions, 2 deletions
diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
index a963b9d766b7..30dbec9fe0b4 100644
--- a/virt/kvm/arm/vgic/vgic-init.c
+++ b/virt/kvm/arm/vgic/vgic-init.c
@@ -348,6 +348,12 @@ void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+ /*
+ * Retire all pending LPIs on this vcpu anyway as we're
+ * going to destroy it.
+ */
+ vgic_flush_pending_lpis(vcpu);
@@ -359,10 +365,10 @@ static void __kvm_vgic_destroy(struct kvm *kvm)
- kvm_vgic_dist_destroy(kvm);
kvm_for_each_vcpu(i, vcpu, kvm)
+ kvm_vgic_dist_destroy(kvm);
void kvm_vgic_destroy(struct kvm *kvm)