drivers/misc/pch_phub.c: don't oops if dmi_get_system_info returns NULL

If dmi_get_system_info() returns NULL, pch_phub_probe() will dereferencea
a zero pointer.

This oops was observed on an Atom based board which has no BIOS, but a
bootloder which doesn't privde DMI data.

Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
Cc: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Cc: Greg KH <gregkh@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/misc/pch_phub.c b/drivers/misc/pch_phub.c
index 5fe79df44838..01eb67b4871a 100644
--- a/drivers/misc/pch_phub.c
+++ b/drivers/misc/pch_phub.c
@@ -686,6 +686,8 @@ static int __devinit pch_phub_probe(struct pci_dev *pdev,
         }
 
         if (id->driver_data == 1) { /* EG20T PCH */
+                const char *board_name;
+
                 retval = sysfs_create_file(&pdev->dev.kobj,
                                            &dev_attr_pch_mac.attr);
                 if (retval)
@@ -701,7 +703,8 @@ static int __devinit pch_phub_probe(struct pci_dev *pdev,
                                                CLKCFG_CANCLK_MASK);
 
                 /* quirk for CM-iTC board */
-                if (strstr(dmi_get_system_info(DMI_BOARD_NAME), "CM-iTC"))
+                board_name = dmi_get_system_info(DMI_BOARD_NAME);
+                if (board_name && strstr(board_name, "CM-iTC"))
                         pch_phub_read_modify_write_reg(chip,
                                                 (unsigned int)CLKCFG_REG_OFFSET,
                                                 CLKCFG_UART_48MHZ | CLKCFG_BAUDDIV |