Bug 2536672 (CVE-2026-90291)

Summary: CVE-2026-90291 kernel: module/dups: Fix use-after-free in kmod_dup_req lifetime handling
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
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   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in the Linux kernel's module duplication handling (`module/dups`). This use-after-free vulnerability arises from incorrect lifetime management of internal request objects. When multiple operations access these objects concurrently, an object can be prematurely freed while still being referenced, potentially leading to system instability or denial of service.
 Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-17 19:04:10 UTC 
In the Linux kernel, the following vulnerability has been resolved:

module/dups: Fix use-after-free in kmod_dup_req lifetime handling

The kmod dups code uses RCU to ensure that a kmod_dup_req instance is freed
only after it is no longer referenced. When releasing an instance, the
kmod_dup_request_delete() function removes the kmod_dup_req from the
dup_kmod_reqs list, waits via synchronize_rcu() and finally frees it.
However, this doesn't work correctly because parallel users referencing the
instance in kmod_dup_request_exists_wait() don't enter an RCU read-side
critical section. This can result in a use-after-free.

The kmod_dup_request_exists_wait() function may need to hold a valid
reference to a kmod_dup_req instance across a blocking wait until the
corresponding modprobe command completes. This makes it unsuitable for RCU.

Fix the issue by changing the lifecycle management of kmod_dup_req to use
reference counting.
Comment 1 gkamathe 2026-09-22 19:00:58 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90291.mbox