iwlagn: fix NULL ptr deref when reprogramming sta w/o LQ

Reinette reports a crash in iwl_reprogram_ap_sta(). The
debugging shows:

  b1 16    mov    $0x16,%cl
 *f3 a5    rep movsl %ds     <-- trapping instruction:(%rsi),%es:(%rdi)

which is a memcpy of 22 (0x16) words (movsl). this points
to "priv->stations[sta_id].lq" being NULL since that is
the memcpy() of that size here.

The only way I see for this to happen is if we try to
do some RXON reprogramming while connecting to an AP,
after tx_sync() but before full setup, but that seems
like something that might very well happen.

Fix this by checking if the LQ is present and only then
reprogramming it.

Reported-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-sta.c b/drivers/net/wireless/iwlwifi/iwl-agn-sta.c
index 93067686218549919b56249a597a66022b8108cb..1b112dfbce779716eb35ff24cf42983aaf0cb5bb 100644 (file)
--- a/drivers/net/wireless/iwlwifi/iwl-agn-sta.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-sta.c
@@ -647,7 +647,7 @@ void iwl_reprogram_ap_sta(struct iwl_priv *priv, struct iwl_rxon_context *ctx)
        int ret;
        struct iwl_addsta_cmd sta_cmd;
        struct iwl_link_quality_cmd lq;
-       bool active;
+       bool active, have_lq = false;
 
        spin_lock_irqsave(&priv->shrd->sta_lock, flags);
        if (!(priv->stations[sta_id].used & IWL_STA_DRIVER_ACTIVE)) {
@@ -657,7 +657,10 @@ void iwl_reprogram_ap_sta(struct iwl_priv *priv, struct iwl_rxon_context *ctx)
 
        memcpy(&sta_cmd, &priv->stations[sta_id].sta, sizeof(sta_cmd));
        sta_cmd.mode = 0;
-       memcpy(&lq, priv->stations[sta_id].lq, sizeof(lq));
+       if (priv->stations[sta_id].lq) {
+               memcpy(&lq, priv->stations[sta_id].lq, sizeof(lq));
+               have_lq = true;
+       }
 
        active = priv->stations[sta_id].used & IWL_STA_UCODE_ACTIVE;
        priv->stations[sta_id].used &= ~IWL_STA_DRIVER_ACTIVE;
@@ -679,7 +682,8 @@ void iwl_reprogram_ap_sta(struct iwl_priv *priv, struct iwl_rxon_context *ctx)
        if (ret)
                IWL_ERR(priv, "failed to re-add STA %pM (%d)\n",
                        priv->stations[sta_id].sta.sta.addr, ret);
-       iwl_send_lq_cmd(priv, ctx, &lq, CMD_SYNC, true);
+       if (have_lq)
+               iwl_send_lq_cmd(priv, ctx, &lq, CMD_SYNC, true);
 }
 
 int iwl_get_free_ucode_key_offset(struct iwl_priv *priv)