From: David Daney <[email protected]> The aer_inject module, when active, replaces the pci_ops structure of the bus so that it can intercept config space accesses. If the config space access needs to be forwarded to the original pci_ops, we must restore the bus's original ops, as the read()/write() functions may require use of the data in the pci_ops structure. An example of such functions are the pci_generic_config*() functions in drivers/pci/access.c. A failure to call these with a valid bus->ops results in dereferencing an invalid bus->ops->map_bus pointer and subsequent OOPs and system crash.
So, do as suggested above. When calling to the original read()/write() functions, temporarily switch back to the original pci_ops. This is safe to do as the pci_lock must already be held, and thus no other users of the bus->ops are possible. Signed-off-by: David Daney <[email protected]> --- drivers/pci/pcie/aer/aer_inject.c | 30 ++++++++++++++++++++++++++++-- 1 file changed, 28 insertions(+), 2 deletions(-) diff --git a/drivers/pci/pcie/aer/aer_inject.c b/drivers/pci/pcie/aer/aer_inject.c index 182224a..2d60e0e 100644 --- a/drivers/pci/pcie/aer/aer_inject.c +++ b/drivers/pci/pcie/aer/aer_inject.c @@ -188,7 +188,9 @@ static int pci_read_aer(struct pci_bus *bus, unsigned int devfn, int where, 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 pci_read_aer(struct pci_bus *bus, unsigned int devfn, int where, } 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 pci_write_aer(struct pci_bus *bus, unsigned int devfn, int where, @@ -220,7 +233,9 @@ static int pci_write_aer(struct pci_bus *bus, unsigned int devfn, int where, 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 pci_write_aer(struct pci_bus *bus, unsigned int devfn, int where, } 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 pci_ops_aer = { -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
