From d92a5d24f9b418119cad5bc1b663eaec4430d7f0 Mon Sep 17 00:00:00 2001 From: "D. Wythe" Date: Wed, 8 Mar 2023 16:17:12 +0800 Subject: [PATCH] net/smc: fix NULL sndbuf_desc in smc_cdc_tx_handler() [ Upstream commit 6d8717541a2f291ebcb7dffbaabf48d37e0d9994 ] When performing a stress test on SMC-R by rmmod mlx5_ib driver during the wrk/nginx test, we found that there is a probability of triggering a panic while terminating all link groups. This issue dues to the race between smc_smcr_terminate_all() and smc_buf_create(). smc_smcr_terminate_all smc_buf_create /* init */ conn->sndbuf_desc = NULL; ... __smc_lgr_terminate smc_conn_kill smc_close_abort smc_cdc_get_slot_and_msg_send __softirqentry_text_start smc_wr_tx_process_cqe smc_cdc_tx_handler READ(conn->sndbuf_desc->len); /* panic dues to NULL sndbuf_desc */ conn->sndbuf_desc = xxx; This patch tries to fix the issue by always to check the sndbuf_desc before send any cdc msg, to make sure that no null pointer is seen during cqe processing. Fixes: 4e35e861bd17 ("net/smc: immediate termination for SMCR link groups") Signed-off-by: D. Wythe Reviewed-by: Tony Lu Reviewed-by: Wenjia Zhang Link: https://lore.kernel.org/r/1678263432-17329-1-git-send-email-alibuda@linux.alibaba.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/smc/smc_cdc.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/smc/smc_cdc.c b/net/smc/smc_cdc.c index 53f63bfbaf5f9..89105e95b4523 100644 --- a/net/smc/smc_cdc.c +++ b/net/smc/smc_cdc.c @@ -114,6 +114,9 @@ int smc_cdc_msg_send(struct smc_connection *conn, union smc_host_cursor cfed; int rc; + if (unlikely(!READ_ONCE(conn->sndbuf_desc))) + return -ENOBUFS; + smc_cdc_add_pending_send(conn, pend); conn->tx_cdc_seq++; -- 2.39.5