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Sat, 24 Oct 2026 21:03:12 -0700 (PDT) Received: from melokc-laptop ([101.90.152.206]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3adeb82761esm2921587a91.0.2026.10.24.21.03.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 24 Oct 2026 21:03:10 -0700 (PDT) From: Anfernee Cao To: D. Wythe , Dust Li , Sidraya Jayagond , Mahanta Jambigi Cc: Tony Lu , Wen Gu , linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH] net/smc: fix possible recursive locking in __smc_lgr_terminate() Date: Sun, 25 Oct 2026 11:53:35 +0800 Message-ID: <179290097759.51540.15412712294727302463@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit syzbot reports a possible recursive locking in the SMC listen path: WARNING: possible recursive locking detected kworker/0:2 is trying to acquire lock: sk_lock-AF_SMC at __smc_lgr_terminate() (net/smc/smc_core.c:1580) but task is already holding lock: sk_lock-AF_SMC at smc_listen_work() (net/smc/af_smc.c:2463) smc_listen_work() holds new_smc->sk while calling smc_listen_decline() -> smc_conn_abort() -> smc_lgr_cleanup_early(). smc_conn_free() unregisters new_smc from lgr->conns_all before the early cleanup, so __smc_lgr_terminate() walks the remaining connections and locks another socket, not the one already held. All sockets use the same sk_lock class, so lockdep cannot tell the two instances apart and reports a possible recursive acquisition. Annotate the per-connection lock as a nested acquisition, as smc_listen_out() already does for the listener socket. Reported-by: syzbot+7ea1f5efd5de7e24f1de@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=7ea1f5efd5de7e24f1de Fixes: 2c7f14ed9c19 ("net/smc: fix LGR and link use-after-free issue") Cc: stable@vger.kernel.org # v6.13+ Signed-off-by: Anfernee Cao --- net/smc/smc_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c index 9974149659c2..5911368ae520 100644 --- a/net/smc/smc_core.c +++ b/net/smc/smc_core.c @@ -1577,7 +1577,7 @@ static void __smc_lgr_terminate(struct smc_link_group *lgr, bool soft) smc = container_of(conn, struct smc_sock, conn); sock_hold(&smc->sk); /* sock_put below */ read_unlock_bh(&lgr->conns_lock); - lock_sock(&smc->sk); + lock_sock_nested(&smc->sk, SINGLE_DEPTH_NESTING); smc_conn_kill(conn, soft); release_sock(&smc->sk); sock_put(&smc->sk); /* sock_hold above */ -- 2.54.0.windows.1