Commit d4a8061a authored Aug 27, 2019 by Heyi Guo Committed by Will Deacon Aug 27, 2019

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: 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>

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);

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