Linux Kernel up to 7.2.5 blk-iocost ioc_pd_free race condition

Summaryinfo

A vulnerability identified as problematic has been detected in Linux Kernel up to 7.2.5. The affected element is the function ioc_pd_free of the component blk-iocost. The manipulation leads to race condition. This vulnerability is traded as CVE-2026-90182. An attack has to be approached locally. There is no exploit available. Applying a patch is the recommended action to fix this issue.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.2.5. It has been rated as problematic. This issue affects the function ioc_pd_free of the component blk-iocost. The manipulation with an unknown input leads to a race condition vulnerability. Using CWE to declare the problem leads to CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. Impacted is availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: blk-iocost: clear delay state when freeing policy data iocg_kick_delay() turns sufficiently large debt into an explicit block-cgroup delay with blkcg_set_delay(), setting blkg->use_delay to -1 and incrementing blkcg->congestion_count. Clearing it again depends on iocg_kick_delay() running from the period timer, the waitq timer or the issue path. ioc_pd_free() removes the iocg from active_iocgs and cancels its waitq timer, and no further bios can arrive, so once it has run nothing is left which can reduce the debt and clear the delay. The blkcg stays marked congested for the rest of its life. blk_cgroup_congested() then returns true for every task in that cgroup and its descendants: page_cache_sync_ra() cuts readahead to a single page, page_cache_async_ra() skips it altogether, and __folio_throttle_swaprate() takes swap_avail_lock and schedules a throttle on anonymous folio allocation. Clear it explicitly, after the list removal and the synchronous hrtimer_cancel() so that neither timer processing nor an I/O path can re-arm it. The free callback can also see policy data which was never attached to a blkg, hence the pd->blkg check.

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2026-90182 since 09/11/2026. The exploitation is known to be easy. An attack has to be approached locally. Additional levels of successful authentication are needed for exploitation. Technical details are known, but no exploit is available.

Applying the patch b9c16db833e3ff15d923282f94dddf0e10fab8c0/97cb95d2148835ae86ff916b145aef332d40439d is able to eliminate this problem.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5

License

• open-source

Website

• Vendor: https://www.kernel.org/

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