Re: [PATCH v2] iwl4965: Fix a null pointer dereference in il_tx_queue_free and il_cmd_queue_free

On Mon, Jan 11, 2016 at 09:42:54PM +0800, Jia-Ju Bai wrote:

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 <baijiaju1990-9Onoh4P/yGk@public.gmane.org>

Acked-by: Stanislaw Gruszka <redacted>

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