netdev - Re: [RFC PATCH net-next] bpf: fix potential percpu map overcopy to user.

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Date:   Thu, 20 Oct 2016 11:41:53 -0700
From:   William Tu <u9012063@...il.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [RFC PATCH net-next] bpf: fix potential percpu map overcopy to user.

On Thu, Oct 20, 2016 at 9:58 AM, Alexei Starovoitov
<alexei.starovoitov@...il.com> wrote:
> On Thu, Oct 20, 2016 at 06:04:38PM +0200, Daniel Borkmann wrote:
>>
>> diff --git a/tools/testing/selftests/bpf/test_maps.c b/tools/testing/selftests/bpf/test_maps.c
>> index ee384f0..d4832e8 100644
>> --- a/tools/testing/selftests/bpf/test_maps.c
>> +++ b/tools/testing/selftests/bpf/test_maps.c
>> @@ -25,6 +25,33 @@
>>
>>  static int map_flags;
>>
>> +static unsigned int num_possible_cpus(void)
>> +{
>> +     static const char *fcpu = "/sys/devices/system/cpu/possible";
>> +     unsigned int val, possible_cpus = 0;
>> +     char buff[128];
>> +     FILE *fp;
>> +
>> +     fp = fopen(fcpu, "r");
>> +     if (!fp) {
>> +             printf("Failed to open %s: '%s'!\n", fcpu, strerror(errno));
>> +             exit(1);
>> +     }
>> +
>> +     while (fgets(buff, sizeof(buff), fp)) {
>> +             if (sscanf(buff, "%*u-%u", &val) == 1)
>> +                     possible_cpus = val;
>> +     }
>
> looks great to me.
> Could you move it into bpf_sys.h or somehow make it common in libbpf
> and reuse it in samples/bpf/ ?
> Since quite a few samples need this fix as well.
> Thanks!
>

Looks good to me. I tested it and it works fine.
Thanks!
William