Bug 2536524 (CVE-2026-92511)

Summary: CVE-2026-92511 kernel: RDMA/core: Fix potential use after free in ib_destroy_cq_user()
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   
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Doc Text:
A flaw was found in the Linux kernel's RDMA (Remote Direct Memory Access) core. A timing issue during the cleanup of a Completion Queue (CQ) when accessed through the netlink path can lead to a use-after-free vulnerability. This could allow an attacker to cause memory corruption, potentially leading to system instability or 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 18:17:56 UTC 
In the Linux kernel, the following vulnerability has been resolved:

RDMA/core: Fix potential use after free in ib_destroy_cq_user()

When accessing a CQ via the netlink path the only synchronization
mechanism for the said CQ is rdma_restrack_get().
Currently, rdma_restrack_del() is invoked at the end of
ib_destroy_cq_user(), which is too late, since by that point
vendor-specific resources associated with the CQ might already be
freed. This can leave a short window where the CQ remains accessible
through restrack, leading to a potential use-after-free.

Fix this by moving the rdma_restrack_begin_del() call to the start of
ib_destroy_cq_user(), ensuring that the CQ is removed from restrack
before its internal resources are released. This guarantees that no new
users hold references to a CQ that is in the process of destruction.

In addition, this change preserves the intended inverted order
between create and destroy routines: resources are added to
restrack at the end of successful creation, and hence shall be removed
from the restrack first thing during the destruction flow, which keeps
the lifecycle management consistent and predictable.
Comment 1 gkamathe 2026-09-21 01:53:18 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-92511.mbox