netdev - Re: 979d63d50c0c0f7bc537bf821e056cc9fe5abd38 bpf: prevent out of bounds speculation on pointer arithmetic

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Message-ID: <c9a89285-23bd-0e4d-3bdc-ea5d5c61e7ff@huawei.com>
Date:   Mon, 11 Mar 2019 19:13:14 +0800
From:   Jason Yan <yanaijie@...wei.com>
To:     Daniel Borkmann <daniel@...earbox.net>
CC:     Jann Horn <jannh@...gle.com>, <ast@...nel.org>,
        <gregkh@...uxfoundation.org>, "zhangyi (F)" <yi.zhang@...wei.com>,
        Zhaohongjiang <zhaohongjiang@...wei.com>,
        <netdev@...r.kernel.org>, <stable@...r.kernel.org>,
        <bpf@...r.kernel.org>
Subject: Re: 979d63d50c0c0f7bc537bf821e056cc9fe5abd38 bpf: prevent out of
 bounds speculation on pointer arithmetic



On 2019/3/11 17:41, Daniel Borkmann wrote:
> Hi Jason,
> 
> On 03/11/2019 10:18 AM, Jason Yan wrote:
>> Hi, Daniel & Greg
>>
>> This patch (979d63d50c0c bpf: prevent out of bounds speculation on pointer arithmetic) was assigned a CVE (CVE-2019-7308) with a high score:
>>
>> CVSS v3.0 Severity and Metrics:
>> Base Score: 9.8 CRITICAL
>>
>> And this patch is not in stable-4.4, would you please backport this patch to 4.4?
> 
> We don't handle kernels as old as 4.4, so someone else would need to
> do the backporting e.g. from your side. The series has been backported
> to the last two most-recent stable kernels at that time (we usually
> follow netdev practice here), and there have been asks about 4.14 as
> well; I've been looking into backporting for the latter last two weeks
> on and off, but there are conflicts all over the place in fragile core
> areas where I didn't have enough free cycles to complete it yet. For
> old kernels, you're probably better off doing something like this in
> your tree instead of the huge complexity with a backport:
> 

Thanks for you kindly reply.

> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index bc34cf9..2cea2de 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -47,7 +47,7 @@ static DEFINE_SPINLOCK(prog_idr_lock);
>   static DEFINE_IDR(map_idr);
>   static DEFINE_SPINLOCK(map_idr_lock);
> 
> -int sysctl_unprivileged_bpf_disabled __read_mostly;
> +int sysctl_unprivileged_bpf_disabled __read_mostly = 1;
> 

Greg, is it possible to get this kind of mitigation into 4.4?

Thanks,
Jason

>   static const struct bpf_map_ops * const bpf_map_types[] = {
>   #define BPF_PROG_TYPE(_id, _ops)
> 
> Thanks,
> Daniel
> 
> .
>