CVE-2026-52908

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.