linux-kernel - Re: [PATCH] mwifiex: fix possible NULL dereference

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Date:	Tue, 12 Apr 2016 17:08:05 +0300
From:	Andy Shevchenko <andy.shevchenko@...il.com>
To:	Sudip Mukherjee <sudipm.mukherjee@...il.com>
Cc:	Amitkumar Karwar <akarwar@...vell.com>,
	Nishant Sarmukadam <nishants@...vell.com>,
	Kalle Valo <kvalo@...eaurora.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"open list:TI WILINK WIRELES..." <linux-wireless@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>,
	Sudip Mukherjee <sudip.mukherjee@...ethink.co.uk>
Subject: Re: [PATCH] mwifiex: fix possible NULL dereference

On Mon, Apr 11, 2016 at 6:27 PM, Sudip Mukherjee
<sudipm.mukherjee@...il.com> wrote:
> From: Sudip Mukherjee <sudip.mukherjee@...ethink.co.uk>
>
> We have a check for card just after dereferencing it. So if it is NULL
> we have already dereferenced it before its check. Lets dereference it
> after checking card for NULL.

IIUC the code does nothing with dereference.

I would have told NAK if I would have been maintainer.

>
> Signed-off-by: Sudip Mukherjee <sudip.mukherjee@...ethink.co.uk>
> ---
>  drivers/net/wireless/marvell/mwifiex/pcie.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/marvell/mwifiex/pcie.c b/drivers/net/wireless/marvell/mwifiex/pcie.c
> index edf8b07..84562d0 100644
> --- a/drivers/net/wireless/marvell/mwifiex/pcie.c
> +++ b/drivers/net/wireless/marvell/mwifiex/pcie.c
> @@ -2884,10 +2884,11 @@ static void mwifiex_unregister_dev(struct mwifiex_adapter *adapter)
>  {
>         struct pcie_service_card *card = adapter->card;

Let's say it's 0.

>         const struct mwifiex_pcie_card_reg *reg;
> -       struct pci_dev *pdev = card->dev;

This would be equal to offset of dev member in pcie_service_card struct.

Nothing wrong here.

> +       struct pci_dev *pdev;
>         int i;
>
>         if (card) {
> +               pdev = card->dev;
>                 if (card->msix_enable) {
>                         for (i = 0; i < MWIFIEX_NUM_MSIX_VECTORS; i++)
>                                 synchronize_irq(card->msix_entries[i].vector);
> --
> 1.9.1
>



-- 
With Best Regards,
Andy Shevchenko