[PATCH 2/2 v2] ATA: piix, fix pointer deref on suspend

[Jiri Slaby <jirislaby@gmail.com>]

Commit
ata_piix: add borked Tecra M4 to broken suspend list
introduced DMI variables checking, but they can be null, so that
we possibly dereference null.

Check if they are null and avoid checks in that case.

Solves:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
IP: [<ffffffff8043da97>] piix_pci_device_suspend+0x117/0x230

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Cc: Jeff Garzik <jgarzik@redhat.com>
Cc: Alexandru Romanescu <a_romanescu@yahoo.co.uk>
Cc: Tejun Heo <tj@kernel.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
---
 drivers/ata/ata_piix.c |   14 +++++++-------
 1 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/ata/ata_piix.c b/drivers/ata/ata_piix.c
index d6d97d8..5fdf167 100644
--- a/drivers/ata/ata_piix.c
+++ b/drivers/ata/ata_piix.c
@@ -1072,13 +1072,13 @@ static int piix_broken_suspend(void)
 	 * matching is necessary because dmi_system_id.matches is
 	 * limited to four entries.
 	 */
-	if (!strcmp(dmi_get_system_info(DMI_SYS_VENDOR), "TOSHIBA") &&
-	    !strcmp(dmi_get_system_info(DMI_PRODUCT_NAME), "000000") &&
-	    !strcmp(dmi_get_system_info(DMI_PRODUCT_VERSION), "000000") &&
-	    !strcmp(dmi_get_system_info(DMI_PRODUCT_SERIAL), "000000") &&
-	    !strcmp(dmi_get_system_info(DMI_BOARD_VENDOR), "TOSHIBA") &&
-	    !strcmp(dmi_get_system_info(DMI_BOARD_NAME), "Portable PC") &&
-	    !strcmp(dmi_get_system_info(DMI_BOARD_VERSION), "Version A0"))
+	if (dmi_match(DMI_SYS_VENDOR, "TOSHIBA") &&
+	    dmi_match(DMI_PRODUCT_NAME, "000000") &&
+	    dmi_match(DMI_PRODUCT_VERSION, "000000") &&
+	    dmi_match(DMI_PRODUCT_SERIAL, "000000") &&
+	    dmi_match(DMI_BOARD_VENDOR, "TOSHIBA") &&
+	    dmi_match(DMI_BOARD_NAME, "Portable PC") &&
+	    dmi_match(DMI_BOARD_VERSION, "Version A0"))
 		return 1;
 
 	return 0;
-- 
1.6.0.5