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    Subject[PATCH AUTOSEL 5.7 238/274] macvlan: Skip loopback packets in RX handler
    Date
    From: Alexander Sverdlin <alexander.sverdlin@nokia.com>

    [ Upstream commit 81f3dc9349ce0bf7b8447f147f45e70f0a5b36a6 ]

    Ignore loopback-originatig packets soon enough and don't try to process L2
    header where it doesn't exist. The very similar br_handle_frame() in bridge
    code performs exactly the same check.

    This is an example of such ICMPv6 packet:

    skb len=96 headroom=40 headlen=96 tailroom=56
    mac=(40,0) net=(40,40) trans=80
    shinfo(txflags=0 nr_frags=0 gso(size=0 type=0 segs=0))
    csum(0xae2e9a2f ip_summed=1 complete_sw=0 valid=0 level=0)
    hash(0xc97ebd88 sw=1 l4=1) proto=0x86dd pkttype=5 iif=24
    dev name=etha01.212 feat=0x0x0000000040005000
    skb headroom: 00000000: 00 7c 86 52 84 88 ff ff 00 00 00 00 00 00 08 00
    skb headroom: 00000010: 45 00 00 9e 5d 5c 40 00 40 11 33 33 00 00 00 01
    skb headroom: 00000020: 02 40 43 80 00 00 86 dd
    skb linear: 00000000: 60 09 88 bd 00 38 3a ff fe 80 00 00 00 00 00 00
    skb linear: 00000010: 00 40 43 ff fe 80 00 00 ff 02 00 00 00 00 00 00
    skb linear: 00000020: 00 00 00 00 00 00 00 01 86 00 61 00 40 00 00 2d
    skb linear: 00000030: 00 00 00 00 00 00 00 00 03 04 40 e0 00 00 01 2c
    skb linear: 00000040: 00 00 00 78 00 00 00 00 fd 5f 42 68 23 87 a8 81
    skb linear: 00000050: 00 00 00 00 00 00 00 00 01 01 02 40 43 80 00 00
    skb tailroom: 00000000: ...
    skb tailroom: 00000010: ...
    skb tailroom: 00000020: ...
    skb tailroom: 00000030: ...

    Call Trace, how it happens exactly:
    ...
    macvlan_handle_frame+0x321/0x425 [macvlan]
    ? macvlan_forward_source+0x110/0x110 [macvlan]
    __netif_receive_skb_core+0x545/0xda0
    ? enqueue_task_fair+0xe5/0x8e0
    ? __netif_receive_skb_one_core+0x36/0x70
    __netif_receive_skb_one_core+0x36/0x70
    process_backlog+0x97/0x140
    net_rx_action+0x1eb/0x350
    ? __hrtimer_run_queues+0x136/0x2e0
    __do_softirq+0xe3/0x383
    do_softirq_own_stack+0x2a/0x40
    </IRQ>
    do_softirq.part.4+0x4e/0x50
    netif_rx_ni+0x60/0xd0
    dev_loopback_xmit+0x83/0xf0
    ip6_finish_output2+0x575/0x590 [ipv6]
    ? ip6_cork_release.isra.1+0x64/0x90 [ipv6]
    ? __ip6_make_skb+0x38d/0x680 [ipv6]
    ? ip6_output+0x6c/0x140 [ipv6]
    ip6_output+0x6c/0x140 [ipv6]
    ip6_send_skb+0x1e/0x60 [ipv6]
    rawv6_sendmsg+0xc4b/0xe10 [ipv6]
    ? proc_put_long+0xd0/0xd0
    ? rw_copy_check_uvector+0x4e/0x110
    ? sock_sendmsg+0x36/0x40
    sock_sendmsg+0x36/0x40
    ___sys_sendmsg+0x2b6/0x2d0
    ? proc_dointvec+0x23/0x30
    ? addrconf_sysctl_forward+0x8d/0x250 [ipv6]
    ? dev_forward_change+0x130/0x130 [ipv6]
    ? _raw_spin_unlock+0x12/0x30
    ? proc_sys_call_handler.isra.14+0x9f/0x110
    ? __call_rcu+0x213/0x510
    ? get_max_files+0x10/0x10
    ? trace_hardirqs_on+0x2c/0xe0
    ? __sys_sendmsg+0x63/0xa0
    __sys_sendmsg+0x63/0xa0
    do_syscall_64+0x6c/0x1e0
    entry_SYSCALL_64_after_hwframe+0x49/0xbe

    Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/net/macvlan.c | 4 ++++
    1 file changed, 4 insertions(+)

    diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
    index 0482adc9916b..e900ebb94499 100644
    --- a/drivers/net/macvlan.c
    +++ b/drivers/net/macvlan.c
    @@ -447,6 +447,10 @@ static rx_handler_result_t macvlan_handle_frame(struct sk_buff **pskb)
    int ret;
    rx_handler_result_t handle_res;

    + /* Packets from dev_loopback_xmit() do not have L2 header, bail out */
    + if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
    + return RX_HANDLER_PASS;
    +
    port = macvlan_port_get_rcu(skb->dev);
    if (is_multicast_ether_addr(eth->h_dest)) {
    unsigned int hash;
    --
    2.25.1
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