Bug 2490786 (CVE-2026-52908)

Summary: CVE-2026-52908 kernel: RDMA: During rereg_mr ensure that REREG_ACCESS is compatible
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: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel. This vulnerability occurs during the re-registration of a Remote Direct Memory Access (RDMA) memory region. If the memory's access permissions are changed from read-only to read-write, the system may fail to properly update and secure the underlying user memory. This improper access control could allow unauthorized write operations to memory that should be protected.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-06-19 15:02:06 UTC 
In the Linux kernel, the following vulnerability has been resolved:

RDMA: During rereg_mr ensure that REREG_ACCESS is compatible

If IB_MR_REREG_ACCESS changes from RO to RW then the umem has to be
re-evaluated to ensure it is properly pinned as RW. Since the umem is
hidden inside each driver's mr struct add a ib_umem_check_rereg() function
that each driver has to call before processing IB_MR_REREG_ACCESS.

mlx4 has to retain its duplicate ib_access_writable check because it
implements IB_MR_REREG_ACCESS | IB_MR_REREG_TRANS by changing both items
in place sequentially while the MR is live, so it will continue to not
support this combination.
Comment 1 Keith Grant 2026-06-22 13:34:26 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026061932-CVE-2026-52908-fb97@gregkh/T