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([2405:4802:1d4a:e90:2022:c2a9:de8:d005]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-39e5647c151sm5267536a91.4.2026.09.20.09.38.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 20 Sep 2026 09:38:10 -0700 (PDT) From: Nguyen Ngoc Thang To: Justin Tee , Naresh Gottumukkala , Paul Ely , Christoph Hellwig , Sagi Grimberg , Chaitanya Kulkarni Cc: Daniel Wagner , Hannes Reinecke , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, syzbot+77955102efac681ec73b@syzkaller.appspotmail.com Subject: [PATCH] nvmet-fcloop: fail LS request synchronously when remote port is gone Date: Sun, 20 Sep 2026 23:38:04 +0700 Message-ID: <20260920163804.67858-1-ngocthang2710.1999@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" fcloop_t2h_ls_req() handles a missing remoteport by queueing the request on tport->ls_list and completing it with -ECONNREFUSED from a work item. nvmet_fc_delete_assoc_work() sends the Disconnect Association LS this way. When it runs during nvmet_fc_unregister_targetport(), the work is queued after flush_workqueue() has started, so it is not waited for. nvmet_fc_free_pending_reqs() then frees the still-pending lsop and the late work item calls lsreq->done() on freed memory: BUG: KASAN: slab-use-after-free in fcloop_rport_lsrqst_work+0x242/0x2e0 Workqueue: nvmet-wq fcloop_tport_lsrqst_work Allocated by nvmet_fc_xmt_disconnect_assoc Freed by nvmet_fc_free_pending_reqs nvmet_fc_unregister_targetport fcloop_delete_target_port Return -ECONNREFUSED directly instead. __nvmet_fc_send_ls_req() unwinds and nvmet_fc_xmt_disconnect_assoc() frees the lsop, so no completion is left outstanding. Reported-by: syzbot+77955102efac681ec73b@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3D77955102efac681ec73b Fixes: bbccbf791e6f ("nvmet-fc: free pending reqs on tgtport unregister") Signed-off-by: Nguyen Ngoc Thang --- drivers/nvme/target/fcloop.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/drivers/nvme/target/fcloop.c b/drivers/nvme/target/fcloop.c index b63af3b643a6..9f9fb40f8a97 100644 --- a/drivers/nvme/target/fcloop.c +++ b/drivers/nvme/target/fcloop.c @@ -456,21 +456,18 @@ fcloop_t2h_ls_req(struct nvmet_fc_target_port *target= port, void *hosthandle, * 1:1 tgtport vs remoteport */ =20 + /* + * Fail synchronously: an async completion can run after + * nvmet_fc_unregister_targetport() has freed the pending lsreq. + */ + if (!tport->remoteport) + return -ECONNREFUSED; + tls_req =3D kmem_cache_alloc(lsreq_cache, GFP_KERNEL); if (!tls_req) return -ENOMEM; tls_req->lsreq =3D lsreq; INIT_LIST_HEAD(&tls_req->ls_list); - - if (!tport->remoteport) { - tls_req->status =3D -ECONNREFUSED; - spin_lock(&tport->lock); - list_add_tail(&tls_req->ls_list, &tport->ls_list); - spin_unlock(&tport->lock); - queue_work(nvmet_wq, &tport->ls_work); - return ret; - } - tls_req->status =3D 0; ret =3D nvme_fc_rcv_ls_req(tport->remoteport, &tls_req->ls_rsp, lsreq->rqstaddr, lsreq->rqstlen); --=20 2.43.0