From: Jacob Keller <jacob.e.keller@intel.com>
To: <intel-wired-lan@osuosl.org>
Subject: Re: [Intel-wired-lan] [net, v1] ice: Fix l2-fwd-offload toggle crash
Date: Mon, 17 Oct 2022 14:13:05 -0700 [thread overview]
Message-ID: <b58bdbc1-9da4-9093-6ebe-7f205cc6b1b3@intel.com> (raw)
In-Reply-To: <CADEbmW0wNym5TJiXeJ+zABb3a5eRvSdPZqWYnDwB6KnXUYK8nQ@mail.gmail.com>
On 10/13/2022 8:25 AM, Michal Schmidt wrote:
> On Wed, Oct 12, 2022 at 6:03 PM Benjamin Mikailenko
> <benjamin.mikailenko@intel.com <mailto:benjamin.mikailenko@intel.com>>
> wrote:
>
> Running netperf traffic and toggling l2-fwd-offload in quick succession
> caused the driver to crash.
>
> BUG: kernel NULL pointer dereference, address: 0000000000000020
> [ 861.517803] #PF: supervisor read access in kernel mode
> [ 861.517805] #PF: error_code(0x0000) - not-present page
> [ 861.517808] PGD 0 P4D 0
> [ 861.517811] Oops: 0000 [#1] PREEMPT SMP PTI
> [ 861.517815] CPU: 60 PID: 16471 Comm: netperf Kdump: loaded
> Tainted: G S
> [ 861.517818] Hardware name: Intel Corporation S2600WTT/S2600WTT,
> BIOS SE
> [ 861.517820] RIP: 0010:ice_start_xmit+0xb0/0x1420 [ice]
>
> This crash would happen because during l2-fwd-offload configuration,
> ice_init_macvlan or ice_deinit_macvlan would temporarily work on Tx
> rings.
>
>
> What are ice_init_macvlan and ice_deinit_macvlan? Are they function
> names? I do not see such functions in the code.
>
>
> At the same time, ice_start_xmit would attempt to select the correct
> send
> buffer from Tx rings but reach a NULL pointer.
>
> Fix this by checking if ring exists before proceeding xmit. If ring does
> not exist, return NETDEV_TX_BUSY.
>
>
> Isn't it still racy though?
> Shouldn't rather whatever is fiddling with the rings make sure the Tx
> queues are stopped first with netif_tx_stop_queue or similar?
> Michal
>
I was going to mention this. No sign of a lock or any other mechanism.
Ideally separately managed structures like this would benefit from
reference counting or such..
Still, sounds like this patch needs to be rejected per other comments.
Thanks,
Jake
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prev parent reply other threads:[~2022-10-17 21:13 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-12 15:55 [Intel-wired-lan] [net,v1] ice: Fix l2-fwd-offload toggle crash Benjamin Mikailenko
2022-10-13 15:25 ` [Intel-wired-lan] [net, v1] " Michal Schmidt
2022-10-13 16:51 ` Benjamin Mikailenko
2022-10-17 21:14 ` Jacob Keller
2022-10-17 21:13 ` Jacob Keller [this message]
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