linux-kernel - Re: KASAN: stack-out-of-bounds Read in __nla

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Date:   Thu, 18 Jan 2018 01:10:46 +0800
From:   Xin Long <lucien.xin@...il.com>
To:     David Ahern <dsahern@...il.com>
Cc:     syzbot <syzbot+03bee3680a37466775e7@...kaller.appspotmail.com>,
        Jason@...c4.com, Andrey Vagin <avagin@...nvz.org>,
        davem <davem@...emloft.net>, David Windsor <dwindsor@...il.com>,
        elena.reshetova@...el.com,
        Herbert Xu <herbert@...dor.apana.org.au>,
        johannes.berg@...el.com, LKML <linux-kernel@...r.kernel.org>,
        network dev <netdev@...r.kernel.org>,
        syzkaller-bugs@...glegroups.com,
        Américo Wang <xiyou.wangcong@...il.com>
Subject: Re: KASAN: stack-out-of-bounds Read in __nla_put

On Thu, Jan 18, 2018 at 12:59 AM, David Ahern <dsahern@...il.com> wrote:
> On 1/17/18 2:39 AM, Xin Long wrote:
>> I guess you need to move up your memset(0) a little bit:
>>
>> @@ -2427,6 +2443,7 @@ int netlink_rcv_skb(struct sk_buff *skb, int
>> (*cb)(struct sk_buff *,
>>                 nlh = nlmsg_hdr(skb);
>>                 err = 0;
>>
>> +               memset(&extack, 0, sizeof(extack));
>>                 if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
>>                         return 0;
>>
>> @@ -2438,7 +2455,6 @@ int netlink_rcv_skb(struct sk_buff *skb, int
>> (*cb)(struct sk_buff *,
>>                 if (nlh->nlmsg_type < NLMSG_MIN_TYPE)
>>                         goto ack;
>>
>> -               memset(&extack, 0, sizeof(extack));
>>                 err = cb(skb, nlh, &extack);
>>
>> So that 'goto ack's won't skip it. :-)
>>
>
> you are correct. Can you submit a patch to do that?
>
sure, if you wish.