| From | Paul Gortmaker <> | Subject | [34-longterm 167/196] iwlwifi: fix skb usage after free | Date | Mon, 12 Mar 2012 20:21:20 -0400 |
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From: Stanislaw Gruszka <sgruszka@redhat.com>
------------------- This is a commit scheduled for the next v2.6.34 longterm release. If you see a problem with using this for longterm, please comment. -------------------
commit b25026981aecde3685dd0e45ad980fff9f528daa upstream.
Since
commit a120e912eb51e347f36c71b60a1d13af74d30e83 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.
[PG: since 34, file renamed, + iwlagn_tx_status --> iwl_tx_status]
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> Acked-by: Wey-Yi Guy <wey-yi.w.guy@intel.com> Signed-off-by: John W. Linville <linville@tuxdriver.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> --- drivers/net/wireless/iwlwifi/iwl-tx.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/net/wireless/iwlwifi/iwl-tx.c b/drivers/net/wireless/iwlwifi/iwl-tx.c index e950153..92a5f9e 100644 --- a/drivers/net/wireless/iwlwifi/iwl-tx.c +++ b/drivers/net/wireless/iwlwifi/iwl-tx.c @@ -1234,11 +1234,15 @@ int iwl_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]; - iwl_tx_status(priv, tx_info->skb[0]); + + if (WARN_ON_ONCE(tx_info->skb == NULL)) + continue; hdr = (struct ieee80211_hdr *)tx_info->skb[0]->data; - if (hdr && ieee80211_is_data_qos(hdr->frame_control)) + if (ieee80211_is_data_qos(hdr->frame_control)) nfreed++; + + iwl_tx_status(priv, tx_info->skb[0]); tx_info->skb[0] = NULL; if (priv->cfg->ops->lib->txq_inval_byte_cnt_tbl) -- 1.7.9.3
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