Commit b2502698 authored by Stanislaw Gruszka's avatar Stanislaw Gruszka Committed by John W. Linville

iwlwifi: fix skb usage after free

Since

commit a120e912
Author: Stanislaw Gruszka <sgruszka@redhat.com>
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: default avatarStanislaw Gruszka <sgruszka@redhat.com>
Acked-by: default avatarWey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 243e6df4
...@@ -1224,12 +1224,16 @@ int iwlagn_tx_queue_reclaim(struct iwl_priv *priv, int txq_id, int index) ...@@ -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)) { q->read_ptr = iwl_queue_inc_wrap(q->read_ptr, q->n_bd)) {
tx_info = &txq->txb[txq->q.read_ptr]; 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; 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++; nfreed++;
iwlagn_tx_status(priv, tx_info,
txq_id >= IWLAGN_FIRST_AMPDU_QUEUE);
tx_info->skb = NULL; tx_info->skb = NULL;
if (priv->cfg->ops->lib->txq_inval_byte_cnt_tbl) if (priv->cfg->ops->lib->txq_inval_byte_cnt_tbl)
......
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