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

[Alexander Lobakin <alexandr.lobakin@intel.com>]

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).

> ---
> 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