Re: [PATCH v2 net-next] fix unsafe set_memory_rw from softirq

[Alexei Starovoitov]

On Thu, Oct 3, 2013 at 4:11 PM, Alexei Starovoitov <ast@xxxxxxxxxxxx> wrote:
> On Thu, Oct 3, 2013 at 4:07 PM, Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote:
>> On Thu, 2013-10-03 at 15:47 -0700, Alexei Starovoitov wrote:
>>
>>> @@ -722,7 +725,8 @@ EXPORT_SYMBOL_GPL(sk_unattached_filter_destroy);
>>>  int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
>>>  {
>>>       struct sk_filter *fp, *old_fp;
>>> -     unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
>>> +     unsigned int fsize = max(sizeof(struct sock_filter) * fprog->len,
>>> +                              sizeof(struct work_struct));
>>>       int err;
>>>
>>>       if (sock_flag(sk, SOCK_FILTER_LOCKED))
>>
>> Thats broken, as we might copy more data from user than expected,
>> and eventually trigger EFAULT :
>>
>> if (copy_from_user(fp->insns, fprog->filter, fsize)) {
>
> yes. will fix.

tested on x86_64/i386 only
with tcpdump and netsniff 1-4k filter size.
Thank you for careful review.
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