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SubjectRe: net/can: warning in raw_setsockopt/__alloc_pages_slowpath
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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.

Regards,
Oliver

>>
>> count = optlen / sizeof(struct can_filter);
>>
>> if (count > 1) {
>> /* filter does not fit into dfilter => alloc space */
>> filter = memdup_user(optval, optlen);
>> if (IS_ERR(filter))
>> return PTR_ERR(filter);
>> } else if (count == 1) {
>> if (copy_from_user(&sfilter, optval, sizeof(sfilter)))
>> return -EFAULT;
>> }
>>
>> lock_sock(sk);
>
> Marc
>

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