From 78e7b15e17ac175e7eed9e21c6f92d03d3b0a6fa Mon Sep 17 00:00:00 2001
From: Radu Rendec <radu.rendec@gmail.com>
Date: Tue, 27 Nov 2018 22:20:48 -0500
Subject: [PATCH] powerpc/msi: Fix NULL pointer access in teardown code
References: bsc#1065729
Patch-mainline: v4.20-rc7
Git-commit: 78e7b15e17ac175e7eed9e21c6f92d03d3b0a6fa
The arch_teardown_msi_irqs() function assumes that controller ops
pointers were already checked in arch_setup_msi_irqs(), but this
assumption is wrong: arch_teardown_msi_irqs() can be called even when
arch_setup_msi_irqs() returns an error (-ENOSYS).
This can happen in the following scenario:
- msi_capability_init() calls pci_msi_setup_msi_irqs()
- pci_msi_setup_msi_irqs() returns -ENOSYS
- msi_capability_init() notices the error and calls free_msi_irqs()
- free_msi_irqs() calls pci_msi_teardown_msi_irqs()
This is easier to see when CONFIG_PCI_MSI_IRQ_DOMAIN is not set and
pci_msi_setup_msi_irqs() and pci_msi_teardown_msi_irqs() are just
aliases to arch_setup_msi_irqs() and arch_teardown_msi_irqs().
The call to free_msi_irqs() upon pci_msi_setup_msi_irqs() failure
seems legit, as it does additional cleanup; e.g.
list_del(&entry->list) and kfree(entry) inside free_msi_irqs() do
happen (MSI descriptors are allocated before pci_msi_setup_msi_irqs()
is called and need to be cleaned up if that fails).
Fixes: 6b2fd7efeb88 ("PCI/MSI/PPC: Remove arch_msi_check_device()")
Cc: stable@vger.kernel.org # v3.18+
Signed-off-by: Radu Rendec <radu.rendec@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
arch/powerpc/kernel/msi.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/msi.c b/arch/powerpc/kernel/msi.c
index dab616a33b8d..f2197654be07 100644
--- a/arch/powerpc/kernel/msi.c
+++ b/arch/powerpc/kernel/msi.c
@@ -34,5 +34,10 @@ void arch_teardown_msi_irqs(struct pci_dev *dev)
{
struct pci_controller *phb = pci_bus_to_host(dev->bus);
- phb->controller_ops.teardown_msi_irqs(dev);
+ /*
+ * We can be called even when arch_setup_msi_irqs() returns -ENOSYS,
+ * so check the pointer again.
+ */
+ if (phb->controller_ops.teardown_msi_irqs)
+ phb->controller_ops.teardown_msi_irqs(dev);
}
--
2.20.1