powerpc/PCI: Fix NULL dereference in sys_pciconfig_iobase() list traversal
authorMike Qiu <qiudayu@linux.vnet.ibm.com>
Mon, 14 Apr 2014 22:12:35 +0000 (16:12 -0600)
committerBjorn Helgaas <bhelgaas@google.com>
Mon, 14 Apr 2014 22:12:35 +0000 (16:12 -0600)
commitff0c41b2df1577f3354f788af4f6bb5dbdfd26da
tree6cc7d886506931f27419040efd98e096508fb501
parentc9eaa447e77efe77b7fa4c953bd62de8297fd6c5
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>
arch/powerpc/kernel/pci_64.c