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Commit 7e8fbdc6 authored by David Daney's avatar David Daney Committed by Bjorn Helgaas
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PCI/AER: Restore pci_ops pointer while calling original pci_ops 



The aer_inject module intercepts config space accesses by replacing the
bus->ops pointer.  If it forwards accesses to the original pci_ops, and
those original ops use bus->ops, they see the aer_pci_ops instead of their
own pci_ops, which can cause a crash.

For example, pci_generic_config_read() uses the bus->ops->map_bus pointer.
If bus->ops is set to aer_pci_ops, which doesn't supply .map_bus,
pci_generic_config_read() will dereference an invalid pointer and cause a
crash.

Temporarily restore the original bus->ops pointer while calling ops->read()
or ops->write().  Callers of these functions already hold pci_lock, which
prevents other users of bus->ops until we're finished.

[bhelgaas: changelog]
Signed-off-by: default avatarDavid Daney <david.daney@cavium.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent 3b0a6d1a

drivers/pci/pcie/aer/aer_inject.c

+28 −2
Original line number Diff line number Diff line
@@ -188,7 +188,9 @@ static int aer_inj_read_config(struct pci_bus *bus, unsigned int devfn, 
	struct aer_error *err;

	unsigned long flags;

	struct pci_ops *ops;

	struct pci_ops *my_ops;

	int domain;

	int rv;



	spin_lock_irqsave(&inject_lock, flags);

	if (size != sizeof(u32))
@@ -208,8 +210,19 @@ static int aer_inj_read_config(struct pci_bus *bus, unsigned int devfn, 
	}

out:

	ops = __find_pci_bus_ops(bus);

	/*

	 * pci_lock must already be held, so we can directly

	 * manipulate bus->ops.  Many config access functions,

	 * including pci_generic_config_read() require the original

	 * bus->ops be installed to function, so temporarily put them

	 * back.

	 */

	my_ops = bus->ops;

	bus->ops = ops;

	rv = ops->read(bus, devfn, where, size, val);

	bus->ops = my_ops;

	spin_unlock_irqrestore(&inject_lock, flags);

	return ops->read(bus, devfn, where, size, val);

	return rv;

}



static int aer_inj_write_config(struct pci_bus *bus, unsigned int devfn,
@@ -220,7 +233,9 @@ static int aer_inj_write_config(struct pci_bus *bus, unsigned int devfn, 
	unsigned long flags;

	int rw1cs;

	struct pci_ops *ops;

	struct pci_ops *my_ops;

	int domain;

	int rv;



	spin_lock_irqsave(&inject_lock, flags);

	if (size != sizeof(u32))
@@ -243,8 +258,19 @@ static int aer_inj_write_config(struct pci_bus *bus, unsigned int devfn, 
	}

out:

	ops = __find_pci_bus_ops(bus);

	/*

	 * pci_lock must already be held, so we can directly

	 * manipulate bus->ops.  Many config access functions,

	 * including pci_generic_config_write() require the original

	 * bus->ops be installed to function, so temporarily put them

	 * back.

	 */

	my_ops = bus->ops;

	bus->ops = ops;

	rv = ops->write(bus, devfn, where, size, val);

	bus->ops = my_ops;

	spin_unlock_irqrestore(&inject_lock, flags);

	return ops->write(bus, devfn, where, size, val);

	return rv;

}



static struct pci_ops aer_inj_pci_ops = {