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Commit d4a8061a authored by Heyi Guo's avatar Heyi Guo Committed by Will Deacon
Browse files

KVM: arm/arm64: vgic: Fix potential deadlock when ap_list is long 



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: 8e444745 ("KVM: arm/arm64: vgic-new: Add IRQ sorting")
Signed-off-by: default avatarZenghui Yu <yuzenghui@huawei.com>
Signed-off-by: default avatarHeyi Guo <guoheyi@huawei.com>
[maz: massaged commit log and patch, added Fixes and Cc-stable]
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 2a1a3fa0

virt/kvm/arm/vgic/vgic.c

+7 −0
Original line number Diff line number Diff line
@@ -254,6 +254,13 @@ 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;



	raw_spin_lock(&irqa->irq_lock);

	raw_spin_lock_nested(&irqb->irq_lock, SINGLE_DEPTH_NESTING);