linux-kernel - Re: net/can: warning in raw_setsockopt/__alloc_pages

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Date:   Fri, 2 Dec 2016 16:42:35 +0100
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Oliver Hartkopp <socketcan@...tkopp.net>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        "David S. Miller" <davem@...emloft.net>, linux-can@...r.kernel.org,
        netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     Dmitry Vyukov <dvyukov@...gle.com>,
        Kostya Serebryany <kcc@...gle.com>,
        syzkaller <syzkaller@...glegroups.com>
Subject: Re: net/can: warning in raw_setsockopt/__alloc_pages_slowpath

On 12/02/2016 04:11 PM, Oliver Hartkopp wrote:
> 
> 
> On 12/02/2016 02:24 PM, Marc Kleine-Budde wrote:
>> On 12/02/2016 01:43 PM, Andrey Konovalov wrote:
> 
> 
>>>  [<ffffffff8369e0de>] raw_setsockopt+0x1be/0x9f0 net/can/raw.c:506
>>
>> We should add a check for a sensible optlen....
>>
>>> static int raw_setsockopt(struct socket *sock, int level, int optname,
>>> 			  char __user *optval, unsigned int optlen)
>>> {
>>> 	struct sock *sk = sock->sk;
>>> 	struct raw_sock *ro = raw_sk(sk);
>>> 	struct can_filter *filter = NULL;  /* dyn. alloc'ed filters */
>>> 	struct can_filter sfilter;         /* single filter */
>>> 	struct net_device *dev = NULL;
>>> 	can_err_mask_t err_mask = 0;
>>> 	int count = 0;
>>> 	int err = 0;
>>>
>>> 	if (level != SOL_CAN_RAW)
>>> 		return -EINVAL;
>>>
>>> 	switch (optname) {
>>>
>>> 	case CAN_RAW_FILTER:
>>> 		if (optlen % sizeof(struct can_filter) != 0)
>>> 			return -EINVAL;
>>
>> here...
>>
>> 		if (optlen > 64 * sizeof(struct can_filter))
>> 			return -EINVAL;
>>
> 
> Agreed.
> 
> But what is sensible here?
> 64 filters is way to small IMO.
> 
> When thinking about picking a bunch of single CAN IDs I would tend to 
> something like 512 filters.

Ok - 64 was just an arbitrary chosen value for demonstration purposes :)

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
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