From 6f7014237405e7f032b5c53a82d9eccf6161c291 Mon Sep 17 00:00:00 2001 From: Ibrahim Hashimov Date: Sun, 12 Jul 2026 14:17:20 +0200 Subject: [PATCH] RDMA/rxe: Fix responder UAF on IB_QP_MAX_DEST_RD_ATOMIC modify_qp rxe_qp_from_attr() handles IB_QP_MAX_DEST_RD_ATOMIC outside the IB_QP_STATE path, so it holds no state_lock and runs while the responder task rxe_receiver() (recv_task on rxe_wq) is live. A modify_qp() setting only that attribute calls free_rd_atomic_resources() then alloc_rd_atomic_resources(), swapping qp->resp.resources[] while rxe_prepare_res()/find_resource() walk it; free_rd_atomic_resources() also leaves the cached pointer qp->resp.res dangling. A local unprivileged user can race the free/realloc into a use-after-free in rxe_receiver() (local DoS). Drain recv_task around the swap with rxe_disable_task()/rxe_enable_task(), as rxe_qp_reset() already does when tearing this array down, re-enabling only after alloc_rd_atomic_resources() succeeds so the responder never resumes against a NULL qp->resp.resources on the ENOMEM path. Also clear qp->resp.res in free_rd_atomic_resources(), like the rxe_resp.c completion paths. Reproduced under KASAN; the slab-use-after-free in rxe_receiver() is gone. Fixes: 8700e3e7c485 ("Soft RoCE driver") Reviewed-by: Zhu Yanjun Signed-off-by: Ibrahim Hashimov Link: https://patch.msgid.link/20260712121720.78001-1-security@auditcode.ai Assisted-by: AuditCode-AI:2026.07 Signed-off-by: Leon Romanovsky --- drivers/infiniband/sw/rxe/rxe_qp.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/drivers/infiniband/sw/rxe/rxe_qp.c b/drivers/infiniband/sw/rxe/rxe_qp.c index 7a0529a17992..ec2cfb12559a 100644 --- a/drivers/infiniband/sw/rxe/rxe_qp.c +++ b/drivers/infiniband/sw/rxe/rxe_qp.c @@ -172,6 +172,7 @@ static void free_rd_atomic_resources(struct rxe_qp *qp) } kfree(qp->resp.resources); qp->resp.resources = NULL; + qp->resp.res = NULL; } } @@ -709,11 +710,23 @@ int rxe_qp_from_attr(struct rxe_qp *qp, struct ib_qp_attr *attr, int mask, qp->attr.max_dest_rd_atomic = max_dest_rd_atomic; + /* + * Not gated by IB_QP_STATE, so the responder task is live. + * Quiesce recv_task like rxe_qp_reset() before swapping the + * rd_atomic array, so rxe_receiver() cannot race the free/ + * realloc. + */ + rxe_disable_task(&qp->recv_task); free_rd_atomic_resources(qp); - err = alloc_rd_atomic_resources(qp, max_dest_rd_atomic); + /* + * On ENOMEM leave recv_task quiesced: qp->resp.resources is + * NULL and rxe_prepare_res()/find_resource() would deref it. + * Re-enable only after a fresh array is installed. + */ if (err) return err; + rxe_enable_task(&qp->recv_task); } if (mask & IB_QP_EN_SQD_ASYNC_NOTIFY)