Re: [PATCH v2 net] ice: arfs: fix use-after-free when freeing @rx_cpu_rmap

[Tony Nguyen <anthony.l.nguyen@intel.com>]

On 4/8/2022 5:31 AM, Alexander Lobakin wrote:
> From: Alexander Lobakin <alexandr.lobakin@intel.com>
> Date: Mon, 4 Apr 2022 18:15:09 +0200
>
>> The CI testing bots triggered the following splat:
>>
>> [  718.203054] BUG: KASAN: use-after-free in free_irq_cpu_rmap+0x53/0x80
>> [  718.206349] Read of size 4 at addr ffff8881bd127e00 by task sh/20834
>> [  718.212852] CPU: 28 PID: 20834 Comm: sh Kdump: loaded Tainted: G S      W IOE     5.17.0-rc8_nextqueue-devqueue-02643-g23f3121aca93 #1
>> [  718.219695] Hardware name: Intel Corporation S2600WFT/S2600WFT, BIOS SE5C620.86B.02.01.0012.070720200218 07/07/2020
>> [  718.223418] Call Trace:
>> [  718.227139]
>> [  718.230783]  dump_stack_lvl+0x33/0x42
>> [  718.234431]  print_address_description.constprop.9+0x21/0x170
>> [  718.238177]  ? free_irq_cpu_rmap+0x53/0x80
>> [  718.241885]  ? free_irq_cpu_rmap+0x53/0x80
>> [  718.245539]  kasan_report.cold.18+0x7f/0x11b
>> [  718.249197]  ? free_irq_cpu_rmap+0x53/0x80
>> [  718.252852]  free_irq_cpu_rmap+0x53/0x80
>> [  718.256471]  ice_free_cpu_rx_rmap.part.11+0x37/0x50 [ice]
>> [  718.260174]  ice_remove_arfs+0x5f/0x70 [ice]
>> [  718.263810]  ice_rebuild_arfs+0x3b/0x70 [ice]
>> [  718.267419]  ice_rebuild+0x39c/0xb60 [ice]
>> [  718.270974]  ? asm_sysvec_apic_timer_interrupt+0x12/0x20
>> [  718.274472]  ? ice_init_phy_user_cfg+0x360/0x360 [ice]
>> [  718.278033]  ? delay_tsc+0x4a/0xb0
>> [  718.281513]  ? preempt_count_sub+0x14/0xc0
>> [  718.284984]  ? delay_tsc+0x8f/0xb0
>> [  718.288463]  ice_do_reset+0x92/0xf0 [ice]
>> [  718.292014]  ice_pci_err_resume+0x91/0xf0 [ice]
>> [  718.295561]  pci_reset_function+0x53/0x80
>> <...>
>> [  718.393035] Allocated by task 690:
>> [  718.433497] Freed by task 20834:
>> [  718.495688] Last potentially related work creation:
>> [  718.568966] The buggy address belongs to the object at ffff8881bd127e00
>>                  which belongs to the cache kmalloc-96 of size 96
>> [  718.574085] The buggy address is located 0 bytes inside of
>>                  96-byte region [ffff8881bd127e00, ffff8881bd127e60)
>> [  718.579265] The buggy address belongs to the page:
>> [  718.598905] Memory state around the buggy address:
>> [  718.601809]  ffff8881bd127d00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
>> [  718.604796]  ffff8881bd127d80: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
>> [  718.607794] >ffff8881bd127e00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
>> [  718.610811]                    ^
>> [  718.613819]  ffff8881bd127e80: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
>> [  718.617107]  ffff8881bd127f00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
>>
>> This is due to that free_irq_cpu_rmap() is always being called
>> *after* (devm_)free_irq() and thus it tries to work with IRQ descs
>> already freed. For example, on device reset the driver frees the
>> rmap right before allocating a new one (the splat above).
>> Make rmap creation and freeing function symmetrical with
>> {request,free}_irq() calls i.e. do that on ifup/ifdown instead
>> of device probe/remove/resume. These operations can be performed
>> independently from the actual device aRFS configuration.
>> Also, make sure ice_vsi_free_irq() clears IRQ affinity notifiers
>> only when aRFS is disabled -- otherwise, CPU rmap sets and clears
>> its own and they must not be touched manually.
>>
>> Fixes: 28bf26724fdb0 ("ice: Implement aRFS")
>> Co-developed-by: Ivan Vecera <ivecera@redhat.com>
>> Signed-off-by: Ivan Vecera <ivecera@redhat.com>
>> Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
> Bah, forgot to mention in v2 that it's an urgent fix. Tony, are you
> okay with posting it to netdev or allowing it to go directly to
> -net? It's been tested by Ivan already (I had also asked Konrad, but
> he hasn't replied yet).

I have another patch to send as well. I'll send that and this one to 
netdev today.

Thanks,

Tony

>> ---
>>  From v1[0]:
>>   - remove the obsolete `!vsi->arfs_fltr_list` check from
>>     ice_free_cpu_rx_rmap() leading to a leak and trace (Ivan).
>>
>> [0] https://lore.kernel.org/netdev/20220404132832.1936529-1-alexandr.lobakin@intel.com
>> ---
> --- 8< ---
>
>> -- 
>> 2.35.1
> Thanks,
> Al