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([221.156.231.192]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b97ac8cf1dsm28160775ad.68.2026.04.28.06.38.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Apr 2026 06:38:20 -0700 (PDT) From: DaeMyung Kang To: Namjae Jeon , Steve French Cc: Sergey Senozhatsky , Tom Talpey , Hyunchul Lee , Bahubali B Gumaji , Sang-Soo Lee , linux-cifs@vger.kernel.org, linux-kernel@vger.kernel.org, DaeMyung Kang Subject: [PATCH] ksmbd: stop transports before procfs cleanup during shutdown Date: Tue, 28 Apr 2026 22:38:16 +0900 Message-ID: <20260428133816.922544-1-charsyam@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-cifs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit ksmbd_server_shutdown() removes the whole /proc/fs/ksmbd subtree via ksmbd_proc_cleanup() before ksmbd_conn_transport_destroy() runs. The transport teardown later calls delete_proc_clients(), which removes the cached proc_clients entry under that subtree. Since proc_remove(ksmbd_proc_fs) already removes the subtree, that later proc_remove(proc_clients) can operate on a freed proc_dir_entry and trip KASAN during rmmod: BUG: KASAN: slab-use-after-free in proc_remove proc_remove ksmbd_conn_transport_destroy ksmbd_server_exit Keep the control sysfs class unregistered before tearing down transports so kill_server cannot race a module-exit cleanup, but stop the transports before removing the root procfs subtree. That lets client and session proc entries be removed while their parent is still alive, then ksmbd_proc_cleanup() can remove the remaining root entries. KASAN testing confirms the ordering issue: the pre-fix module reproduces the proc_remove slab-use-after-free during rmmod, while the patched module passes the same rmmod scenario. Active pending-IO testing also passes; the observed workqueue hog warning is present on the pre-fix baseline as well and is not introduced by this shutdown ordering change. Fixes: b38f99c1217a ("ksmbd: add procfs interface for runtime monitoring and statistics") Signed-off-by: DaeMyung Kang --- fs/smb/server/server.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/smb/server/server.c b/fs/smb/server/server.c index 5d799b2d4c62..188a6a72f7fa 100644 --- a/fs/smb/server/server.c +++ b/fs/smb/server/server.c @@ -535,11 +535,11 @@ static int ksmbd_server_shutdown(void) { WRITE_ONCE(server_conf.state, SERVER_STATE_SHUTTING_DOWN); - ksmbd_proc_cleanup(); class_unregister(&ksmbd_control_class); + ksmbd_conn_transport_destroy(); + ksmbd_proc_cleanup(); ksmbd_workqueue_destroy(); ksmbd_ipc_release(); - ksmbd_conn_transport_destroy(); ksmbd_crypto_destroy(); ksmbd_free_global_file_table(); destroy_lease_table(NULL); -- 2.43.0