linux-kernel - Re: [PATCH] usb: musb: Fix potential NULL dereference

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Message-ID: <CAJs94EaFU+9stV5CW138eLvxnERR9VRaoLDci86gDMRW63LNfA@mail.gmail.com>
Date:   Thu, 24 Jan 2019 21:47:02 +0300
From:   "Matwey V. Kornilov" <matwey.kornilov@...il.com>
To:     Bin Liu <b-liu@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     "open list:MUSB MULTIPOINT HIGH SPEED DUAL-ROLE CONTROLLER" 
        <linux-usb@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: musb: Fix potential NULL dereference

By the way, why do we need to store the qh in urb->hcpriv?
qh can always be accessible through urb->ep->hcpriv
Wouldn't it be better to drop entire urb->hcpriv usage?

ср, 23 янв. 2019 г. в 20:52, Matwey V. Kornilov <matwey@....msu.ru>:
>
> We assign "urb->hcpriv = qh;" a few lines down. The valid qh for the urb is
> hep->hcpriv in this code path.
>
> Fixes: 714bc5ef3eda ("musb: potential use after free")
> Signed-off-by: Matwey V. Kornilov <matwey@....msu.ru>
> ---
>  drivers/usb/musb/musb_host.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
> index c6118a962d37..6f267716768e 100644
> --- a/drivers/usb/musb/musb_host.c
> +++ b/drivers/usb/musb/musb_host.c
> @@ -2336,7 +2336,7 @@ static int musb_urb_enqueue(
>                  * odd, rare, error prone, but legal.
>                  */
>                 kfree(qh);
> -               qh = NULL;
> +               qh = hep->hcpriv;
>                 ret = 0;
>         } else
>                 ret = musb_schedule(musb, qh,
> --
> 2.16.4
>


-- 
With best regards,
Matwey V. Kornilov