UBUNTU-CVE-2026-89530: Critical severity ubuntu/linux-hwe-edge vulnerability

In the Linux kernel, the following vulnerability has been resolved: svcrdma: Reject inline replies that overflow the pull-up buffer An RPC-over-RDMA client can request a reply, such as an NFS READ payload, without providing a Write list or a Reply chunk to carry it. When such a reply needs more scatter/gather entries than the device's Send Queue supports, svcrdmapullupneeded() selects pull-up and svcrdmapullupreplymsg() linearizes the whole reply into sctxt->scxprtbuf. That buffer is only scmaxreqsize bytes, while the reply on this path is bounded only by the client's request, so svcrdmaxblinearize() copies past the end of the buffer and corrupts adjacent slab memory. The oversized length is then stored in scsges[0].length and posted, so the device also reads beyond the mapped region. The SGE-exhaustion branch is the only pull-up path that can exceed the buffer: the threshold branch pulls up only replies smaller than RPCRDMAPULLUPTHRESH, and replies that fit the device's SGE budget are sent directly without linearization. Make svcrdmapullupneeded() report -E2BIG when the reply it would pull up cannot fit scmaxreqsize, and fail the request with ERRCHUNK as RFC 8166 Section 4.5.3 directs rather than dropping the connection. The helper no longer answers a simple yes/no question: it now reports pull-up, no pull-up, or -E2BIG for a reply too large to linearize. Rename svcrdmapullupneeded() to svcrdmacheckpullup() so its name no longer implies a boolean predicate.