Re: [PATCH 4.4 04/35] iwlwifi: pcie: add a NULL check in iwl_pcie_txq_unmap

Nobuhiro Iwamatsu
2021-02-25T06:09:10Z

Hi,

Sorry for the report after the release.

On Mon, Feb 22, 2021 at 01:36:00PM +0100, Greg Kroah-Hartman wrote:
> From: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
>
> [ Upstream commit 98c7d21f957b10d9c07a3a60a3a5a8f326a197e5 ]
>
> I hit a NULL pointer exception in this function when the
> init flow went really bad.
>
> Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
> Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
> Link: https://lore.kernel.org/r/iwlwifi.20210115130252.2e8da9f2c132.I0234d4b8ddaf70aaa5028a20c863255e05bc1f84@changeid
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> drivers/net/wireless/iwlwifi/pcie/tx.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/net/wireless/iwlwifi/pcie/tx.c b/drivers/net/wireless/iwlwifi/pcie/tx.c
> index 8dfe6b2bc7031..cb03c2855019b 100644
> --- a/drivers/net/wireless/iwlwifi/pcie/tx.c
> +++ b/drivers/net/wireless/iwlwifi/pcie/tx.c
> @@ -585,6 +585,11 @@ static void iwl_pcie_txq_unmap(struct iwl_trans *trans, int txq_id)
> struct iwl_txq *txq = &trans_pcie->txq[txq_id];
> struct iwl_queue *q = &txq->q;
>
> + if (!txq) {
> + IWL_ERR(trans, "Trying to free a queue that wasn't allocated?\n");
> + return;
> + }
> +

I think that this fix is not enough.
If txq is NULL, an error will occur with "struct iwl_queue * q = & txq->q;".
The following changes are required.

diff --git a/drivers/net/wireless/iwlwifi/pcie/tx.c b/drivers/net/wireless/iwlwifi/pcie/tx.c
index cb03c2855019b7..7584796131fa41 100644
--- a/drivers/net/wireless/iwlwifi/pcie/tx.c
+++ b/drivers/net/wireless/iwlwifi/pcie/tx.c
@@ -583,13 +583,15 @@ static void iwl_pcie_txq_unmap(struct iwl_trans *trans, int txq_id)
{
struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
struct iwl_txq *txq = &trans_pcie->txq[txq_id];
- struct iwl_queue *q = &txq->q;
+ struct iwl_queue *q;

if (!txq) {
IWL_ERR(trans, "Trying to free a queue that wasn't allocated?\n");
return;
}

+ q = &txq->q;
+
spin_lock_bh(&txq->lock);
while (q->write_ptr != q->read_ptr) {
IWL_DEBUG_TX_REPLY(trans, "Q %d Free %d\n",

> spin_lock_bh(&txq->lock);
> while (q->write_ptr != q->read_ptr) {
> IWL_DEBUG_TX_REPLY(trans, "Q %d Free %d\n",
> --
> 2.27.0
>
>

Best regards,
Nobuhiro