From: Eric Dumazet <eric.dumazet@gmail.com>
To: Cong Wang <xiyou.wangcong@gmail.com>,
syzbot+37b8770e6d5a8220a039@syzkaller.appspotmail.com
Cc: David Miller <davem@davemloft.net>,
Jamal Hadi Salim <jhs@mojatatu.com>,
Jiri Pirko <jiri@resnulli.us>,
LKML <linux-kernel@vger.kernel.org>,
Linux Kernel Network Developers <netdev@vger.kernel.org>,
syzkaller-bugs@googlegroups.com
Subject: Re: KASAN: use-after-free Read in tcf_block_find
Date: Wed, 26 Sep 2018 14:50:42 -0700 [thread overview]
Message-ID: <7fcb1c03-6976-9b34-601d-5f50b74c5b0a@gmail.com> (raw)
In-Reply-To: <CAM_iQpXxzR3GP4wK7z+wW_0-vC9cuyiwnrCYqx+NpBgDvBXLcg@mail.gmail.com>
On 09/26/2018 02:44 PM, Cong Wang wrote:
> On Wed, Sep 26, 2018 at 8:44 AM syzbot
> <syzbot+37b8770e6d5a8220a039@syzkaller.appspotmail.com> wrote:
>>
>> Hello,
>>
>> syzbot found the following crash on:
>>
>> HEAD commit: 4b1bd6976945 net: phy: marvell: Fix build.
>> git tree: net-next
>> console output: https://syzkaller.appspot.com/x/log.txt?x=16f763fa400000
>> kernel config: https://syzkaller.appspot.com/x/.config?x=443816db871edd66
>> dashboard link: https://syzkaller.appspot.com/bug?extid=37b8770e6d5a8220a039
>> compiler: gcc (GCC) 8.0.1 20180413 (experimental)
>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17a5614e400000
>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=141a532a400000
>>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: syzbot+37b8770e6d5a8220a039@syzkaller.appspotmail.com
>>
>> IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
>> 8021q: adding VLAN 0 to HW filter on device team0
>> ==================================================================
>> BUG: KASAN: use-after-free in tcf_block_find+0x9d1/0xb90
>> net/sched/cls_api.c:646
>> Read of size 4 at addr ffff8801cc126978 by task syz-executor002/5646
>>
>> CPU: 1 PID: 5646 Comm: syz-executor002 Not tainted 4.19.0-rc5+ #232
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
>> Google 01/01/2011
>> Call Trace:
>> __dump_stack lib/dump_stack.c:77 [inline]
>> dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113
>> print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
>> kasan_report_error mm/kasan/report.c:354 [inline]
>> kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
>> __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
>> tcf_block_find+0x9d1/0xb90 net/sched/cls_api.c:646
>
> Hmm. looks like missing a rcu_dereference() here:
>
> if (!*parent) {
> *q = dev->qdisc;
> *parent = (*q)->handle;
>
We hold RTNL here.
Have we already done the changes allowing dev->qdisc being changed
without RTNL being required ?
next prev parent reply other threads:[~2018-09-26 21:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-26 15:44 KASAN: use-after-free Read in tcf_block_find syzbot
2018-09-26 21:44 ` Cong Wang
2018-09-26 21:50 ` Eric Dumazet [this message]
2018-09-26 21:55 ` Cong Wang
2018-09-27 8:06 ` Dmitry Vyukov
2018-09-27 8:10 ` Dmitry Vyukov
2018-09-27 13:00 ` Eric Dumazet
2018-09-27 13:02 ` Dmitry Vyukov
2018-09-27 13:24 ` Eric Dumazet
2018-09-27 13:42 ` Dmitry Vyukov
2018-09-27 17:50 ` Cong Wang
2018-09-27 18:04 ` Dmitry Vyukov
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