Bug 2536797 (CVE-2026-90389)

Summary: CVE-2026-90389 kernel: md: scope memalloc_noio to allocation critical sections
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Doc Text:
A flaw was found in the Linux kernel. A concurrency issue in the Multiple Device (MD) subsystem's handling of `memalloc_noio_save()` tokens can occur during concurrent suspend sysfs writes. This allows a task to return to userspace while still within a `PF_MEMALLOC_NOIO` scope, enabling another task to restore a previously saved token. This could lead to unexpected system behavior or resource management issues, potentially resulting in a denial of service.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-17 19:34:17 UTC 
In the Linux kernel, the following vulnerability has been resolved:

md: scope memalloc_noio to allocation critical sections

Storing a memalloc_noio_save() token in mddev->noio_flags lets one task
save the token and another task restore it. With concurrent suspend sysfs
writes, task A can enter PF_MEMALLOC_NOIO, return to userspace still in
that scope, and later task B can restore A's saved token.

Avoid tying the token lifetime to mddev. Keep mddev_suspend() and
mddev_resume() only responsible for array suspension, and enter
PF_MEMALLOC_NOIO only in the MD paths that allocate memory after the array
has been suspended. Restore the token before resuming the array.

A reproducer repeatedly writes suspend_lo and suspend_hi from concurrent
workers and checks each worker's /proc/self/stat flags before and after the
sysfs write.
Comment 1 gkamathe 2026-09-21 07:56:18 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90389.mbox