Re: [External] Re: [Intel-wired-lan] [PATCH v2] ixgbe: Fix NULL pointer dereference in ixgbe_xdp_setup

[Jesper Dangaard Brouer <jbrouer@redhat.com>]

Hi Feng and Jason,

Please notice that you are both developing patches that change the ixgbe 
driver in related areas.

Jason's patch:
  Subject: [PATCH v7] ixgbe: let the xdpdrv work with more than 64 cpus
 
https://lore.kernel.org/all/20210901101206.50274-1-kerneljasonxing@gmail.com/

We might need both as this patch looks like a fix to a panic, and 
Jason's patch allows XDP on ixgbe to work on machines with more than 64 
CPUs.

-Jesper

On 06/09/2021 09.49, Feng Zhou wrote:
> 
> 在 2021/9/6 下午2:37, Paul Menzel 写道:
>> Dear Feng,
>>
>>
>> Am 03.09.21 um 08:40 schrieb Feng zhou:
>>
>> (If you care, in your email client, your last name does not start with 
>> a capital letter.)
>>
>>> From: Feng Zhou <zhoufeng.zf@bytedance.com>
>>>
>>> The ixgbe driver currently generates a NULL pointer dereference with
>>> some machine (online cpus < 63). This is due to the fact that the
>>> maximum value of num_xdp_queues is nr_cpu_ids. Code is in
>>> "ixgbe_set_rss_queues"".
>>>
>>> Here's how the problem repeats itself:
>>> Some machine (online cpus < 63), And user set num_queues to 63 through
>>> ethtool. Code is in the "ixgbe_set_channels",
>>> adapter->ring_feature[RING_F_FDIR].limit = count;
>>
>> For better legibility, you might want to indent code (blocks) by four 
>> spaces and add blank lines around it (also below).
>>
>>> It becames 63.
>>
>> becomes
>>
>>> When user use xdp, "ixgbe_set_rss_queues" will set queues num.
>>> adapter->num_rx_queues = rss_i;
>>> adapter->num_tx_queues = rss_i;
>>> adapter->num_xdp_queues = ixgbe_xdp_queues(adapter);
>>> And rss_i's value is from
>>> f = &adapter->ring_feature[RING_F_FDIR];
>>> rss_i = f->indices = f->limit;
>>> So "num_rx_queues" > "num_xdp_queues", when run to "ixgbe_xdp_setup",
>>> for (i = 0; i < adapter->num_rx_queues; i++)
>>>     if (adapter->xdp_ring[i]->xsk_umem)
>>> lead to panic.
>>
>> lead*s*?
>>
>>> Call trace:
>>> [exception RIP: ixgbe_xdp+368]
>>> RIP: ffffffffc02a76a0  RSP: ffff9fe16202f8d0  RFLAGS: 00010297
>>> RAX: 0000000000000000  RBX: 0000000000000020  RCX: 0000000000000000
>>> RDX: 0000000000000000  RSI: 000000000000001c  RDI: ffffffffa94ead90
>>> RBP: ffff92f8f24c0c18   R8: 0000000000000000   R9: 0000000000000000
>>> R10: ffff9fe16202f830  R11: 0000000000000000  R12: ffff92f8f24c0000
>>> R13: ffff9fe16202fc01  R14: 000000000000000a  R15: ffffffffc02a7530
>>> ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
>>>   7 [ffff9fe16202f8f0] dev_xdp_install at ffffffffa89fbbcc
>>>   8 [ffff9fe16202f920] dev_change_xdp_fd at ffffffffa8a08808
>>>   9 [ffff9fe16202f960] do_setlink at ffffffffa8a20235
>>> 10 [ffff9fe16202fa88] rtnl_setlink at ffffffffa8a20384
>>> 11 [ffff9fe16202fc78] rtnetlink_rcv_msg at ffffffffa8a1a8dd
>>> 12 [ffff9fe16202fcf0] netlink_rcv_skb at ffffffffa8a717eb
>>> 13 [ffff9fe16202fd40] netlink_unicast at ffffffffa8a70f88
>>> 14 [ffff9fe16202fd80] netlink_sendmsg at ffffffffa8a71319
>>> 15 [ffff9fe16202fdf0] sock_sendmsg at ffffffffa89df290
>>> 16 [ffff9fe16202fe08] __sys_sendto at ffffffffa89e19c8
>>> 17 [ffff9fe16202ff30] __x64_sys_sendto at ffffffffa89e1a64
>>> 18 [ffff9fe16202ff38] do_syscall_64 at ffffffffa84042b9
>>> 19 [ffff9fe16202ff50] entry_SYSCALL_64_after_hwframe at ffffffffa8c0008c
>>
>> Please describe the fix in the commit message.
>>
>>> Fixes: 4a9b32f30f80 ("ixgbe: fix potential RX buffer starvation for
>>> AF_XDP")
>>> Signed-off-by: Feng Zhou <zhoufeng.zf@bytedance.com>
>>> ---
>>> Updates since v1:
>>> - Fix "ixgbe_max_channels" callback so that it will not allow a 
>>> setting of
>>> queues to be higher than the num_online_cpus().
>>> more details can be seen from here:
>>> https://patchwork.ozlabs.org/project/intel-wired-lan/patch/20210817075407.11961-1-zhoufeng.zf@bytedance.com/ 
>>>
>>> Thanks to Maciej Fijalkowski for your advice.
>>>
>>>   drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c | 2 +-
>>>   drivers/net/ethernet/intel/ixgbe/ixgbe_main.c    | 8 ++++++--
>>>   2 files changed, 7 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c 
>>> b/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c
>>> index 4ceaca0f6ce3..21321d164708 100644
>>> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c
>>> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c
>>> @@ -3204,7 +3204,7 @@ static unsigned int ixgbe_max_channels(struct 
>>> ixgbe_adapter *adapter)
>>>           max_combined = ixgbe_max_rss_indices(adapter);
>>>       }
>>>   -    return max_combined;
>>> +    return min_t(int, max_combined, num_online_cpus());
>>>   }
>>>     static void ixgbe_get_channels(struct net_device *dev,
>>> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c 
>>> b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
>>> index 14aea40da50f..5db496cc5070 100644
>>> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
>>> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
>>> @@ -10112,6 +10112,7 @@ static int ixgbe_xdp_setup(struct net_device 
>>> *dev, struct bpf_prog *prog)
>>>       struct ixgbe_adapter *adapter = netdev_priv(dev);
>>>       struct bpf_prog *old_prog;
>>>       bool need_reset;
>>> +    int num_queues;
>>>         if (adapter->flags & IXGBE_FLAG_SRIOV_ENABLED)
>>>           return -EINVAL;
>>> @@ -10161,11 +10162,14 @@ static int ixgbe_xdp_setup(struct 
>>> net_device *dev, struct bpf_prog *prog)
>>>       /* Kick start the NAPI context if there is an AF_XDP socket open
>>>        * on that queue id. This so that receiving will start.
>>>        */
>>> -    if (need_reset && prog)
>>> -        for (i = 0; i < adapter->num_rx_queues; i++)
>>> +    if (need_reset && prog) {
>>> +        num_queues = min_t(int, adapter->num_rx_queues,
>>> +            adapter->num_xdp_queues);
>>> +        for (i = 0; i < num_queues; i++)
>>>               if (adapter->xdp_ring[i]->xsk_pool)
>>>                   (void)ixgbe_xsk_wakeup(adapter->netdev, i,
>>>                                  XDP_WAKEUP_RX);
>>> +    }
>>>         return 0;
>>>   }
>>>
> Thanks for your advice. I will modify the commit message in v3
>