irqchip/gic-v2m: Prevent use after free of gicv2m_get_fwnode()

[ Upstream commit 3318dc299b072a0511d6dfd8367f3304fb6d9827 ]

With ACPI in place, gicv2m_get_fwnode() is registered with the pci
subsystem as pci_msi_get_fwnode_cb(), which may get invoked at runtime
during a PCI host bridge probe. But, the call back is wrongly marked as
__init, causing it to be freed, while being registered with the PCI
subsystem and could trigger:

 Unable to handle kernel paging request at virtual address ffff8000816c0400
  gicv2m_get_fwnode+0x0/0x58 (P)
  pci_set_bus_msi_domain+0x74/0x88
  pci_register_host_bridge+0x194/0x548

This is easily reproducible on a Juno board with ACPI boot.

Retain the function for later use.

Fixes: 0644b3daca28 ("irqchip/gic-v2m: acpi: Introducing GICv2m ACPI support")
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/irqchip/irq-gic-v2m.c b/drivers/irqchip/irq-gic-v2m.c
index 6790a621a9324c703e3aa29f80bc6eaf4f6a1755..9d99b19cd21b6f80fc6c1ead802367b23992eff9 100644 (file)
--- a/drivers/irqchip/irq-gic-v2m.c
+++ b/drivers/irqchip/irq-gic-v2m.c
@@ -455,7 +455,7 @@ static int __init gicv2m_of_init(struct fwnode_handle *parent_handle,
 #ifdef CONFIG_ACPI
 static int acpi_num_msi;
 
-static __init struct fwnode_handle *gicv2m_get_fwnode(struct device *dev)
+static struct fwnode_handle *gicv2m_get_fwnode(struct device *dev)
 {
        struct v2m_data *data;