7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Aohan Mei commit 492ba6ac1b1ffb8a06ff52db0825c1af2cdb28c8 upstream. rds_rdma_cm_event_handler_cmn() assigns trans only when the RDMA device is an InfiniBand CA (RDMA_NODE_IB_CA). On any other device type, e.g. an iWARP RNIC such as siw, trans stays uninitialized, but the event switch dereferences it: unconditionally in the RDMA_CM_EVENT_CONNECT_REQUEST case via trans->cm_handle_connect(), and (with a connection context) in the ROUTE_RESOLVED and ESTABLISHED cases. An RDS listener on an iWARP device therefore crashes the kernel as soon as a connect request arrives: with CONFIG_INIT_STACK_ALL_ZERO the wild load becomes a NULL dereference at offset 0xa0 (&trans->cm_handle_connect) in the iw_cm_wq workqueue. GCC masks the bug in default builds by folding the uninitialized load into &rds_ib_transport; Clang-built kernels take the real uninitialized path and oops. The active side can land on a non-IB device too: the id that rds_ib_conn_path_connect() creates is not restricted to a node type, so rdma_resolve_addr() binds it to whichever device serves the local address, and an iWARP RNIC on the same netdev qualifies. The crash there is different: resolving a route on an iWARP id never fills in cm_id->route.path_rec, and the ROUTE_RESOLVED case writes path_rec[0].sl before it calls into the transport. The iWARP transport was dropped long ago and IB is the only transport left, so make that explicit: initialize trans to &rds_ib_transport at declaration, drop the conditional assignment, reject a connect request that arrives on a non-IB device, and drop a connection whose address resolved to one instead of resolving a route on it. The rejection is limited to RDMA_CM_EVENT_CONNECT_REQUEST on purpose: a non-zero return from the handler makes rdma_cm destroy the id the event was delivered on, which is right for the request's freshly created id but would free a connection id that RDS still owns for any other event. On the active side the id stays ic->i_cm_id and the connection's shutdown destroys it, so that case returns 0. Fixes: dcdede0406d3 ("RDS: Drop stale iWARP RDMA transport") Reported-by: TencentOS Corvus AI Link: https://lore.kernel.org/netdev/20260824111701.2979194-1-ljp1205831794@gmail.com/ Link: https://lore.kernel.org/netdev/20260825021223.3483044-1-ljp1205831794@gmail.com/ Cc: stable@vger.kernel.org Assisted-by: CodeBuddy:Kimi-K3 Signed-off-by: Aohan Mei [achender: reject only on RDMA_CM_EVENT_CONNECT_REQUEST instead of bailing out for every event on a non-IB device, so that rdma_cm does not destroy connection ids RDS still tracks; drop a connection whose address resolved to a non-IB device before a route is resolved on it; changelog adjusted] Assisted-by: LLM Signed-off-by: Allison Henderson Link: https://patch.msgid.link/20261003163408.250568-2-achender@kernel.org Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman --- net/rds/rdma_transport.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) --- a/net/rds/rdma_transport.c +++ b/net/rds/rdma_transport.c @@ -52,7 +52,7 @@ static int rds_rdma_cm_event_handler_cmn { /* this can be null in the listening path */ struct rds_connection *conn = cm_id->context; - struct rds_transport *trans; + struct rds_transport *trans = &rds_ib_transport; int ret = 0; int *err; u8 len; @@ -60,9 +60,6 @@ static int rds_rdma_cm_event_handler_cmn rdsdebug("conn %p id %p handling event %u (%s)\n", conn, cm_id, event->event, rdma_event_msg(event->event)); - if (cm_id->device->node_type == RDMA_NODE_IB_CA) - trans = &rds_ib_transport; - /* Prevent shutdown from tearing down the connection * while we're executing. */ if (conn) { @@ -82,11 +79,32 @@ static int rds_rdma_cm_event_handler_cmn switch (event->event) { case RDMA_CM_EVENT_CONNECT_REQUEST: + /* Only the IB transport is supported, but RDS listens on + * every RDMA device: reject a request that arrived on any + * other kind. A non-zero return has rdma_cm destroy the + * request's id, which is what we want here and only here. + */ + if (cm_id->device->node_type != RDMA_NODE_IB_CA) { + ret = 1; + break; + } ret = trans->cm_handle_connect(cm_id, event, isv6); break; case RDMA_CM_EVENT_ADDR_RESOLVED: if (conn) { + /* The address resolved to a device RDS has no + * transport for. Do not go on to resolve a route: + * an iWARP route leaves cm_id->route.path_rec + * unset, which the ROUTE_RESOLVED case below + * dereferences. Drop the connection instead; the + * id is still ic->i_cm_id, so return 0 and let the + * shutdown destroy it. + */ + if (cm_id->device->node_type != RDMA_NODE_IB_CA) { + rds_conn_drop(conn); + break; + } rdma_set_service_type(cm_id, conn->c_tos); rdma_set_min_rnr_timer(cm_id, IB_RNR_TIMER_000_32); ret = rdma_resolve_route(cm_id,