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Subject: Re: KASAN: slab-out-of-bounds Read in bpf_skb_vlan_push
To:     syzbot <syzbot+76de61614cb1abdd73fc@syzkaller.appspotmail.com>,
        ast@kernel.org, davem@davemloft.net, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com
References: <000000000000219be6056e8850fa@google.com>
From:   Daniel Borkmann <daniel@iogearbox.net>
Message-ID: <b3af0f35-b0f8-859d-4f8f-b919d35ebaaa@iogearbox.net>
Date:   Wed, 13 Jun 2018 20:13:22 +0200
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On 06/13/2018 06:17 PM, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    75d4e704fa8d netdev-FAQ: clarify DaveM's position for stab..
> git tree:       bpf-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=1754783f800000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=a601a80fec461d44
> dashboard link: https://syzkaller.appspot.com/bug?extid=76de61614cb1abdd73fc
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=12c1e1bf800000
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+76de61614cb1abdd73fc@syzkaller.appspotmail.com
> 
> IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready
> IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
> 8021q: adding VLAN 0 to HW filter on device team0
> 8021q: adding VLAN 0 to HW filter on device team0
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in skb_at_tc_ingress include/net/sch_generic.h:535 [inline]
> BUG: KASAN: slab-out-of-bounds in bpf_push_mac_rcsum net/core/filter.c:1625 [inline]
> BUG: KASAN: slab-out-of-bounds in ____bpf_skb_vlan_push net/core/filter.c:2446 [inline]
> BUG: KASAN: slab-out-of-bounds in bpf_skb_vlan_push+0x6b7/0x720 net/core/filter.c:2437
> Read of size 5 at addr ffff8801b77347d0 by task syz-executor6/6529

Should be fixed already by:

  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=58990d1ff3f7896ee341030e9a7c2e4002570683


#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git