iwlegacy: 4965-rs: avoid null pointer dereference error

il4965_rs_initialize_lq checks to see if sta is null, however, before that
check il4965_rs_use_green dereferences sta when intializing use_green.
Avoid a potential null pointer dereference error by only calling
il4965_rs_use_green after we are sure sta is not null.

Smatch analysis:

drivers/net/wireless/iwlegacy/4965-rs.c:2160 il4965_rs_initialize_lq() warn:
  variable dereferenced before check 'sta' (see line 2155)

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/iwlegacy/4965-rs.c b/drivers/net/wireless/iwlegacy/4965-rs.c
index e8324b5..6c7493c 100644 (file)
--- a/drivers/net/wireless/iwlegacy/4965-rs.c
+++ b/drivers/net/wireless/iwlegacy/4965-rs.c
@@ -2152,7 +2152,7 @@ il4965_rs_initialize_lq(struct il_priv *il, struct ieee80211_conf *conf,
        int rate_idx;
        int i;
        u32 rate;
-       u8 use_green = il4965_rs_use_green(il, sta);
+       u8 use_green;
        u8 active_tbl = 0;
        u8 valid_tx_ant;
        struct il_station_priv *sta_priv;
@@ -2160,6 +2160,7 @@ il4965_rs_initialize_lq(struct il_priv *il, struct ieee80211_conf *conf,
        if (!sta || !lq_sta)
                return;
 
+       use_green = il4965_rs_use_green(il, sta);
        sta_priv = (void *)sta->drv_priv;
 
        i = lq_sta->last_txrate_idx;