CVE-2024-36908: blk-iocost: do not WARN if iocg was already offlined

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-05-30 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: blk-iocost: do not WARN if iocg was already offlined In iocg_pay_debt(), warn is triggered if 'active_list' is empty, which is intended to confirm iocg is active when it has debt. However, warn can be triggered during a blkcg or disk removal, if iocg_waitq_timer_fn() is run at that time: WARNING: CPU: 0 PID: 2344971 at block/blk-iocost.c:1402 iocg_pay_debt+0x14c/0x190 Call trace: iocg_pay_debt+0x14c/0x190 iocg_kick_waitq+0x438/0x4c0 iocg_waitq_timer_fn+0xd8/0x130 __run_hrtimer+0x144/0x45c __hrtimer_run_queues+0x16c/0x244 hrtimer_interrupt+0x2cc/0x7b0 The warn in this situation is meaningless. Since this iocg is being removed, the state of the 'active_list' is irrelevant, and 'waitq_timer' is canceled after removing 'active_list' in ioc_pd_free(), which ensures iocg is freed after iocg_waitq_timer_fn() returns. Therefore, add the check if iocg was already offlined to avoid warn when removing a blkcg or disk.

Affected products

Linux kernel: from 5.4 before 5.10.237; from 5.11 before 5.15.181; from 5.16 before 6.1.135; from 6.2 before 6.6.31; from 6.7 before 6.8.10; 6.9-rc1, 6.9-rc2, 6.9-rc3, 6.9-rc4 — fixed in 5.10.237, 5.15.181, 6.1.135, 6.6.31, 6.8.10

How to fix

Upgrade to a fixed version: Linux kernel 5.10.237, 5.15.181, 6.1.135, 6.6.31. Check the vendor advisory for mitigations.

References

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