AZL-99519

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

RDMA/rxe: Fix responder UAF on IBQPMAXDESTRDATOMIC modifyqp

rxeqpfromattr() handles IBQPMAXDESTRDATOMIC outside the IBQPSTATE path, so it holds no statelock and runs while the responder task rxereceiver() (recvtask on rxewq) is live. A modifyqp() setting only that attribute calls freerdatomicresources() then allocrdatomicresources(), swapping qp->resp.resources[] while rxeprepareres()/findresource() walk it; freerdatomicresources() also leaves the cached pointer qp->resp.res dangling. A local unprivileged user can race the free/realloc into a use-after-free in rxereceiver() (local DoS).

Drain recvtask around the swap with rxedisabletask()/rxeenabletask(), as rxeqpreset() already does when tearing this array down, re-enabling only after allocrdatomicresources() succeeds so the responder never resumes against a NULL qp->resp.resources on the ENOMEM path. Also clear qp->resp.res in freerdatomicresources(), like the rxeresp.c completion paths.

Reproduced under KASAN; the slab-use-after-free in rxe_receiver() is gone.