Bug 2516807 (CVE-2026-74334)

Summary: CVE-2026-74334 kernel: RDMA/nldev: Fix locking when accessing mr->pd
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the RDMA/nldev component of the Linux kernel. Improper locking during memory region re-registration (rereg_mr) can lead to a race condition when accessing protection domains (PD). This vulnerability could result in unpredictable system behavior or a denial of service due to concurrent, unsynchronized memory access.
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Description OSIDB Bzimport 2026-08-15 06:34:29 UTC 
In the Linux kernel, the following vulnerability has been resolved:

RDMA/nldev: Fix locking when accessing mr->pd

Sashiko points out that, due to rereg_mr, the PD is actually variable and
all the touches in nldev are racy.

Use mr->device instead of mr->pd->device.

Getting the PD restrack ID is more tricky. To avoid disturbing all the
happy paths, add an rdma_restrack_sync() operation which is sort of like
flush_workqueue() or synchronize_irq(): after it returns, all the old
nldev touches to the mr are gone and everything sees the new PD. This
makes it safe to reach into the PD pointer.
Comment 1 gkamathe 2026-08-19 10:07:35 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081556-CVE-2026-74334-dadf@gregkh/T