From b25026981aecde3685dd0e45ad980fff9f528daa Mon Sep 17 00:00:00 2001 From: Stanislaw Gruszka Date: Wed, 20 Apr 2011 15:57:14 +0200 Subject: [PATCH] iwlwifi: fix skb usage after free Since commit a120e912eb51e347f36c71b60a1d13af74d30e83 Author: Stanislaw Gruszka Date: Fri Feb 19 15:47:33 2010 -0800 iwlwifi: sanity check before counting number of tfds can be free we use skb->data after calling ieee80211_tx_status_irqsafe(), which could free skb instantly. On current kernels I do not observe practical problems related with bug, but on 2.6.35.y it cause random system hangs when stressing wireless link. Cc: stable@kernel.org # 2.6.32+ Signed-off-by: Stanislaw Gruszka Acked-by: Wey-Yi Guy Signed-off-by: John W. Linville --- drivers/net/wireless/iwlwifi/iwl-agn-tx.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-tx.c b/drivers/net/wireless/iwlwifi/iwl-agn-tx.c index a709d05c5868..2dd7d54a796f 100644 --- a/drivers/net/wireless/iwlwifi/iwl-agn-tx.c +++ b/drivers/net/wireless/iwlwifi/iwl-agn-tx.c @@ -1224,12 +1224,16 @@ int iwlagn_tx_queue_reclaim(struct iwl_priv *priv, int txq_id, int index) q->read_ptr = iwl_queue_inc_wrap(q->read_ptr, q->n_bd)) { tx_info = &txq->txb[txq->q.read_ptr]; - iwlagn_tx_status(priv, tx_info, - txq_id >= IWLAGN_FIRST_AMPDU_QUEUE); + + if (WARN_ON_ONCE(tx_info->skb == NULL)) + continue; hdr = (struct ieee80211_hdr *)tx_info->skb->data; - if (hdr && ieee80211_is_data_qos(hdr->frame_control)) + if (ieee80211_is_data_qos(hdr->frame_control)) nfreed++; + + iwlagn_tx_status(priv, tx_info, + txq_id >= IWLAGN_FIRST_AMPDU_QUEUE); tx_info->skb = NULL; if (priv->cfg->ops->lib->txq_inval_byte_cnt_tbl) -- 2.20.1