ice: arfs: fix use-after-free when freeing @rx_cpu_rmap
CVE: CVE-2022-49063
Component: kernel
CWE: CWE-825
Severity: Moderate
CVSS v3: 7.4/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Release date: 2022-01-01T00:00:00+00:00

In the Linux kernel, the following vulnerability has been resolved:

ice: arfs: fix use-after-free when freeing @rx_cpu_rmap

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.


Remediation:
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.