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[128.210.106.74]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-315867bc341sm14727379eec.27.2026.08.04.14.39.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Aug 2026 14:39:24 -0700 (PDT) From: Yifei Gao To: "D . Wythe" , Dust Li , Sidraya Jayagond , Mahanta Jambigi , linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org, netdev@vger.kernel.org Cc: Tony Lu , Wen Gu , Karsten Graul , Ursula Braun , Wenjia Zhang , linux-kernel@vger.kernel.org, Yifei Gao , stable@vger.kernel.org Subject: [PATCH] net/smc: fix sock refcount leak in smc_switch_conns() error path Date: Tue, 4 Aug 2026 21:39:17 +0000 Message-ID: <20260804213917.3413525-1-gyf161023@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" smc_switch_conns() takes a reference on the socket with sock_hold() before dropping conns_lock to prefetch a tx slot. On success the reference is released by the sock_put() after smc_switch_cursor(). When smc_cdc_get_free_slot() fails, however, the function jumps straight to err_out without a sock_put(), leaking the reference and leaving the socket unreclaimable. During SMC-R link failover with an exhausted backup link this leaks one reference per failing connection switch. Release the reference before jumping to err_out. The err_out label is also reached from the smc_switch_cursor() failure path, which has already done its own sock_put(), so the put must stay at the get_free_slot failure site rather than at the label. Fixes: c6f02ebeea3a ("net/smc: switch connections to alternate link") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Yifei Gao --- net/smc/smc_core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c index cf6b620fef05..04c6ce608ec7 100644 --- a/net/smc/smc_core.c +++ b/net/smc/smc_core.c @@ -1148,8 +1148,10 @@ struct smc_link *smc_switch_conns(struct smc_link_gr= oup *lgr, read_unlock_bh(&lgr->conns_lock); /* pre-fetch buffer outside of send_lock, might sleep */ rc =3D smc_cdc_get_free_slot(conn, to_lnk, &wr_buf, NULL, &pend); - if (rc) + if (rc) { + sock_put(&smc->sk); goto err_out; + } /* avoid race with smcr_tx_sndbuf_nonempty() */ spin_lock_bh(&conn->send_lock); smc_switch_link_and_count(conn, to_lnk); --=20 2.43.0