CVE-2026-74390: RDMA/irdma: Fix out-of-bounds write in irdma_copy_user_pgaddrs

In the Linux kernel, the following vulnerability has been resolved:

RDMA/irdma: Fix out-of-bounds write in irdmacopyuserpgaddrs

The irdmacopyuserpgaddrs function loops through all of the umem DMA blocks to populate the PBLEs and will stop when either the last DMA block is reached or palloc->totalcnt is reached. The issue is that the logic for checking palloc->totalcnt would only work for non-zero values.

When irdmasetuppbles is called with lvl==0, it calls irdmacopyuserpgaddrs with palloc->totalcnt==0, which means the only way to break out of the loop is to reach the last umem DMA block, which means it could end up going beyond the fixed size of 4 iwmr->pgaddrmem array that is used in the lvl==0 case.

In the case of QP/CQ/SRQ rings, the value of lvl is determined by a separate input (for example, req.cqpages in the case of a CQ). So, we must perform explicit checking to ensure we don't overflow the pgaddrmem array if the user provides a umem that consists of more blocks than their provided req.cqpages.