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

From: Jason Xing
Date: Tue Sep 07 2021 - 22:37:46 EST

On Mon, Sep 6, 2021 at 7:32 PM Jesper Dangaard Brouer
<jbrouer@xxxxxxxxxx> wrote:
>
> Hi Feng and Jason,
>
> Please notice that you are both developing patches that change the ixgbe
> driver in related areas.

Thanks for noticing. We're doing different things as they are both
related to XDP on ixgbe actually.

Jason

>
> 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@xxxxxxxxx/
>
> 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@xxxxxxxxxxxxx>
> >>>
> >>> 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@xxxxxxxxxxxxx>
> >>> ---
> >>> 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@xxxxxxxxxxxxx/
> >>>
> >>> 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
> >
>