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iwl4965: Fix a null pointer dereference in il_tx_queue_free and il_cmd_queue_free

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If "txq->cmd = kzalloc(...)" in il_tx_queue_init fails,
"kfree(txq->cmd[i])" in il_tx_queue_free and il_cmd_queue_free
in iwl4965_hw_txq_ctx_free will causes a null pointer dereference,
because txq->cmd is NULL at that time.

This patch fixes this problem by adding a if-check before kfree.
To avoid double free in il_tx_queue_free and il_cmd_queue_free
caused by the fixing, txq->meta and txq->cmd in error handling code
of il_tx_queue_init are assigned null values.
Otherwise, a double free will occur.

This patch has been tested in real device, and it actually fixes the bug.
Thanks Stanislaw for his suggestion.

Signed-off-by: Jia-Ju Bai <baijiaju1990@163.com>
Acked-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Julian Calaby <julian.calaby@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
This commit is contained in:
Jia-Ju Bai 2016-03-18 13:24:06 +11:00 committed by Kalle Valo
parent fb9693f045
commit fe9b47944e
1 changed files with 10 additions and 4 deletions
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14
drivers/net/wireless/intel/iwlegacy/common.c
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@ -2792,8 +2792,10 @@ il_tx_queue_free(struct il_priv *il, int txq_id)
il_tx_queue_unmap(il, txq_id);
/* De-alloc array of command/tx buffers */
for (i = 0; i < TFD_TX_CMD_SLOTS; i++)
kfree(txq->cmd[i]);
if (txq->cmd) {
for (i = 0; i < TFD_TX_CMD_SLOTS; i++)
kfree(txq->cmd[i]);
}
/* De-alloc circular buffer of TFDs */
if (txq->q.n_bd)
@ -2871,8 +2873,10 @@ il_cmd_queue_free(struct il_priv *il)
il_cmd_queue_unmap(il);
/* De-alloc array of command/tx buffers */
for (i = 0; i <= TFD_CMD_SLOTS; i++)
kfree(txq->cmd[i]);
if (txq->cmd) {
for (i = 0; i <= TFD_CMD_SLOTS; i++)
kfree(txq->cmd[i]);
}
/* De-alloc circular buffer of TFDs */
if (txq->q.n_bd)
@ -3078,7 +3082,9 @@ err:
kfree(txq->cmd[i]);
out_free_arrays:
kfree(txq->meta);
txq->meta = NULL;
kfree(txq->cmd);
txq->cmd = NULL;
return -ENOMEM;
}