powerpc/PCI: Fix NULL dereference in sys_pciconfig_iobase() list traversal
3bc955987fb3 ("powerpc/PCI: Use list_for_each_entry() for bus traversal")
caused a NULL pointer dereference because the loop body set the iterator to
NULL:
Unable to handle kernel paging request for data at address 0x00000000
Faulting instruction address: 0xc000000000041d78
Oops: Kernel access of bad area, sig: 11 [#1]
...
NIP [c000000000041d78] .sys_pciconfig_iobase+0x68/0x1f0
LR [c000000000041e0c] .sys_pciconfig_iobase+0xfc/0x1f0
Call Trace:
[c0000003b4787db0] [c000000000041e0c] .sys_pciconfig_iobase+0xfc/0x1f0 (unreliable)
[c0000003b4787e30] [c000000000009ed8] syscall_exit+0x0/0x98
Fix it by using a temporary variable for the iterator.
[bhelgaas: changelog, drop tmp_bus initialization]
Fixes: 3bc955987fb3 powerpc/PCI: Use list_for_each_entry() for bus traversal
Signed-off-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/arch/powerpc/kernel/pci_64.c b/arch/powerpc/kernel/pci_64.c
index 2a47790..155013d 100644
--- a/arch/powerpc/kernel/pci_64.c
+++ b/arch/powerpc/kernel/pci_64.c
@@ -208,7 +208,7 @@
unsigned long in_devfn)
{
struct pci_controller* hose;
- struct pci_bus *bus = NULL;
+ struct pci_bus *tmp_bus, *bus = NULL;
struct device_node *hose_node;
/* Argh ! Please forgive me for that hack, but that's the
@@ -229,10 +229,12 @@
* used on pre-domains setup. We return the first match
*/
- list_for_each_entry(bus, &pci_root_buses, node) {
- if (in_bus >= bus->number && in_bus <= bus->busn_res.end)
+ list_for_each_entry(tmp_bus, &pci_root_buses, node) {
+ if (in_bus >= tmp_bus->number &&
+ in_bus <= tmp_bus->busn_res.end) {
+ bus = tmp_bus;
break;
- bus = NULL;
+ }
}
if (bus == NULL || bus->dev.of_node == NULL)
return -ENODEV;
