linux-kernel - Re: [PATCH] gdm7240: Add check for NULL for callback in r

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Message-ID: <Y4HgF21MXyb9YH+h@kadam>
Date:   Sat, 26 Nov 2022 12:44:55 +0300
From:   Dan Carpenter <error27@...il.com>
To:     Ekaterina Esina <eesina@...ralinux.ru>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Won Kang <wkang77@...il.com>, linux-staging@...ts.linux.dev,
        linux-kernel@...r.kernel.org, lvc-project@...uxtesting.org
Subject: Re: [PATCH] gdm7240: Add check for NULL for callback in r

On Wed, Nov 23, 2022 at 04:23:45PM +0300, Ekaterina Esina wrote:
> Before dereferencing r->callback check it for NULL.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> Fixes: 61e121047645 ("staging: gdm7240: adding LTE USB driver")
> Signed-off-by: Ekaterina Esina <eesina@...ralinux.ru>
> ---
>  drivers/staging/gdm724x/gdm_usb.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/gdm724x/gdm_usb.c b/drivers/staging/gdm724x/gdm_usb.c
> index 54bdb64f52e8..7cf89f4c95c4 100644
> --- a/drivers/staging/gdm724x/gdm_usb.c
> +++ b/drivers/staging/gdm724x/gdm_usb.c
> @@ -409,10 +409,12 @@ static void do_rx(struct work_struct *work)
>  		switch (cmd_evt) {
>  		case LTE_GET_INFORMATION_RESULT:
>  			if (set_mac_address(hci->data, r->cb_data) == 0) {
> -				r->callback(r->cb_data,
> +				if (r->callback) {

What makes you think r->callback can be NULL?

So far as I can see that's not possible.  It is checked before it's
added to the list in gdm_usb_rcv_complete().

regards,
dan carpenter