p54: fix a NULL pointer dereference bug

If the RSSI calibration table was not found or not parsed properly,
priv->rssi_db will be NULL, p54_rssi_find needs to be able to deal
with that.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Acked-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/net/wireless/p54/eeprom.c b/drivers/net/wireless/p54/eeprom.c
index f54e15fcd623..13d750da9301 100644
--- a/drivers/net/wireless/p54/eeprom.c
+++ b/drivers/net/wireless/p54/eeprom.c
@@ -524,10 +524,13 @@ err_data:
 
 struct p54_rssi_db_entry *p54_rssi_find(struct p54_common *priv, const u16 freq)
 {
-        struct p54_rssi_db_entry *entry = (void *)(priv->rssi_db->data +
-                                                   priv->rssi_db->offset);
+        struct p54_rssi_db_entry *entry;
         int i, found = -1;
 
+        if (!priv->rssi_db)
+                return &p54_rssi_default;
+
+        entry = (void *)(priv->rssi_db->data + priv->rssi_db->offset);
         for (i = 0; i < priv->rssi_db->entries; i++) {
                 if (!same_band(freq, entry[i].freq))
                         continue;