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authorHeyi Guo <guoheyi@huawei.com>2019-08-27 12:26:50 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-09-06 10:19:53 +0200
commitf35eb8a3aa3b492489116965558c3f2f7d641f31 (patch)
tree135860cedbebbfd8af5d7983b438f040db3b7242 /virt
parentc251d5c53246042dacf485340cb244af92f1f78c (diff)
KVM: arm/arm64: vgic: Fix potential deadlock when ap_list is long
[ Upstream commit d4a8061a7c5f7c27a2dc002ee4cb89b3e6637e44 ] If the ap_list is longer than 256 entries, merge_final() in list_sort() will call the comparison callback with the same element twice, causing a deadlock in vgic_irq_cmp(). Fix it by returning early when irqa == irqb. Cc: stable@vger.kernel.org # 4.7+ Fixes: 8e4447457965 ("KVM: arm/arm64: vgic-new: Add IRQ sorting") Signed-off-by: Zenghui Yu <yuzenghui@huawei.com> Signed-off-by: Heyi Guo <guoheyi@huawei.com> [maz: massaged commit log and patch, added Fixes and Cc-stable] Signed-off-by: Marc Zyngier <maz@kernel.org> Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/arm/vgic/vgic.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 6440b56ec90e..1934dc8a2ce0 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -196,6 +196,13 @@ static int vgic_irq_cmp(void *priv, struct list_head *a, struct list_head *b)
bool penda, pendb;
int ret;
+ /*
+ * list_sort may call this function with the same element when
+ * the list is fairly long.
+ */
+ if (unlikely(irqa == irqb))
+ return 0;
+
spin_lock(&irqa->irq_lock);
spin_lock_nested(&irqb->irq_lock, SINGLE_DEPTH_NESTING);