parisc: Fix out of array access in match_pci_device()

As found by the ubsan checker, the value of the 'index' variable can be
out of range for the bc[] array:

UBSAN: Undefined behaviour in arch/parisc/kernel/drivers.c:655:21
index 6 is out of range for type 'char [6]'
Backtrace:
 [<104fa850>] __ubsan_handle_out_of_bounds+0x68/0x80
 [<1019d83c>] check_parent+0xc0/0x170
 [<1019d91c>] descend_children+0x30/0x6c
 [<1059e164>] device_for_each_child+0x60/0x98
 [<1019cd54>] parse_tree_node+0x40/0x54
 [<1019d86c>] check_parent+0xf0/0x170
 [<1019d91c>] descend_children+0x30/0x6c
 [<1059e164>] device_for_each_child+0x60/0x98
 [<1019d938>] descend_children+0x4c/0x6c
 [<1059e164>] device_for_each_child+0x60/0x98
 [<1019cd54>] parse_tree_node+0x40/0x54
 [<1019cffc>] hwpath_to_device+0xa4/0xc4

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: stable@vger.kernel.org

diff --git a/arch/parisc/kernel/drivers.c b/arch/parisc/kernel/drivers.c
index 6afb595e0d86c47e0105606bb544ca6a83188617..3b8507f710507dcd141d0d11f550d53722a0bd7c 100644 (file)
--- a/arch/parisc/kernel/drivers.c
+++ b/arch/parisc/kernel/drivers.c
@@ -651,6 +651,10 @@ static int match_pci_device(struct device *dev, int index,
                                        (modpath->mod == PCI_FUNC(devfn)));
        }
 
+       /* index might be out of bounds for bc[] */
+       if (index >= 6)
+               return 0;
+
        id = PCI_SLOT(pdev->devfn) | (PCI_FUNC(pdev->devfn) << 5);
        return (modpath->bc[index] == id);
 }