ssb: fix NULL ptr deref when pcihost_wrapper is used

Ethernet driver b44 does register ssb by it's pcihost_wrapper
and doesn't set ssb_chipcommon. A check on this value
introduced with commit d53cdbb94a52a920d5420ed64d986c3523a56743
and ea2db495f92ad2cf3301623e60cb95b4062bc484 triggers:

BUG: unable to handle kernel NULL pointer dereference at 00000010
IP: [<c1266c36>] ssb_is_sprom_available+0x16/0x30

Signed-off-by: Christoph Fritz <chf.fritz@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 7 insertions, 3 deletions

diff --git a/drivers/ssb/pci.c b/drivers/ssb/pci.c
index 989e2752cc36..6dcda86be6eb 100644
--- a/drivers/ssb/pci.c
+++ b/drivers/ssb/pci.c
@@ -625,9 +625,12 @@ static int ssb_pci_sprom_get(struct ssb_bus *bus,
                 ssb_printk(KERN_ERR PFX "No SPROM available!\n");
                 return -ENODEV;
         }
-
-        bus->sprom_offset = (bus->chipco.dev->id.revision < 31) ?
-                SSB_SPROM_BASE1 : SSB_SPROM_BASE31;
+        if (bus->chipco.dev) {  /* can be unavailible! */
+                bus->sprom_offset = (bus->chipco.dev->id.revision < 31) ?
+                        SSB_SPROM_BASE1 : SSB_SPROM_BASE31;
+        } else {
+                bus->sprom_offset = SSB_SPROM_BASE1;
+        }
 
         buf = kcalloc(SSB_SPROMSIZE_WORDS_R123, sizeof(u16), GFP_KERNEL);
         if (!buf)
diff --git a/drivers/ssb/sprom.c b/drivers/ssb/sprom.c
index 007bc3a03486..4f7cc8d13277 100644
--- a/drivers/ssb/sprom.c
+++ b/drivers/ssb/sprom.c
@@ -185,6 +185,7 @@ bool ssb_is_sprom_available(struct ssb_bus *bus)
         /* this routine differs from specs as we do not access SPROM directly
            on PCMCIA */
         if (bus->bustype == SSB_BUSTYPE_PCI &&
+            bus->chipco.dev &&  /* can be unavailible! */
             bus->chipco.dev->id.revision >= 31)
                 return bus->chipco.capabilities & SSB_CHIPCO_CAP_SPROM;