6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Shubham Antil [ Upstream commit 65cf6863606b0507a7c3bd1711317e4f5d6b8b7e ] rds_ib_process_recv() accounts every receive fragment as contributing min(i_recv_data_rem, RDS_FRAG_SIZE) bytes, regardless of the completion length. When a completion is shorter than the header-declared amount, receive accounting can advance beyond the payload supplied by the completion. Only an IB_WC_RECV completion has the buffer layout expected by this receive path. Other successful completion opcodes must not be interpreted as ordinary receive completions. Reject successful completions with any other opcode before processing their length. For ordinary receive completions, require enough payload to cover the amount accounted to the fragment before linking its page into the incoming message. This is compatible with the current transmit paths. MSG_ZEROCOPY is restricted to RDS/TCP, while RDS/IB copied and page-vector messages use full-sized non-final scatterlist entries. Found during an LLM-assisted source audit and validated under KMSAN with a malformed short receive completion. Reported-by: sungbyeongchan Closes: https://lore.kernel.org/netdev/20261006205204.1322102-1-tjdqudcks0424@naver.com/ Reported-by: Giovanni Vignone Link: https://lore.kernel.org/netdev/8a6ee1d5336ae65b8ffdc8c40a1135657207e204.camel@kernel.org/ Reported-by: Robert van Eijk Link: https://lore.kernel.org/netdev/8a6ee1d5336ae65b8ffdc8c40a1135657207e204.camel@kernel.org/ Reported-by: Paolo Gentry Link: https://lore.kernel.org/netdev/8a6ee1d5336ae65b8ffdc8c40a1135657207e204.camel@kernel.org/ Fixes: 1e23b3ee0e94 ("RDS/IB: Receive datagrams via IB") Cc: stable@vger.kernel.org Signed-off-by: Shubham Antil Reviewed-by: Allison Henderson Link: https://patch.msgid.link/20261013025729.40815-1-shubham@octane.security Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/rds/ib_recv.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c index 0b52e060988d5..ad4ff441bc983 100644 --- a/net/rds/ib_recv.c +++ b/net/rds/ib_recv.c @@ -949,6 +949,12 @@ static void rds_ib_process_recv(struct rds_connection *conn, } } + if (data_len < min_t(u32, ic->i_recv_data_rem, RDS_FRAG_SIZE)) { + rds_ib_conn_error(conn, + "fragment shorter than header-declared length; forcing reconnect\n"); + goto done; + } + list_add_tail(&recv->r_frag->f_item, &ibinc->ii_frags); recv->r_frag = NULL; @@ -1004,7 +1010,12 @@ void rds_ib_recv_cqe_handler(struct rds_ib_connection *ic, * event is processed. */ if (wc->status == IB_WC_SUCCESS) { - rds_ib_process_recv(conn, recv, wc->byte_len, state); + if (wc->opcode != IB_WC_RECV) + rds_ib_conn_error(conn, + "recv completion had unexpected opcode %u, disconnecting and reconnecting\n", + wc->opcode); + else + rds_ib_process_recv(conn, recv, wc->byte_len, state); } else { /* We expect errors as the qp is drained during shutdown */ if (rds_conn_up(conn) || rds_conn_connecting(conn)) -- 2.53.0