On Mon, Aug 26, 2024 at 8:57 PM gregkh@linuxfoundation.org wrote:

Hi Greg,

The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

Could you please apply the attached backport patch for linux 6.6 stable kernel ?

Thanks!

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 76e98a158b207771a6c9a0de0a60522a446a3447 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024082626-succulent-engraver-73cd@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

76e98a158b20 ("ksmbd: fix race condition between destroy_previous_session() and smb2 operations()") d484d621d40f ("ksmbd: add durable scavenger timer") c8efcc786146 ("ksmbd: add support for durable handles v1/v2") fa9415d4024f ("ksmbd: mark SMB2_SESSION_EXPIRED to session when destroying previous session") c2a721eead71 ("ksmbd: lazy v2 lease break on smb2_write()") d47d9886aeef ("ksmbd: send v2 lease break notification for directory") eb547407f357 ("ksmbd: downgrade RWH lease caching state to RH for directory") 2e450920d58b ("ksmbd: move oplock handling after unlock parent dir") 4274a9dc6aeb ("ksmbd: separately allocate ci per dentry") 864fb5d37163 ("ksmbd: fix possible deadlock in smb2_open")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 76e98a158b207771a6c9a0de0a60522a446a3447 Mon Sep 17 00:00:00 2001 From: Namjae Jeon linkinjeon@kernel.org Date: Sat, 17 Aug 2024 14:03:49 +0900 Subject: [PATCH] ksmbd: fix race condition between destroy_previous_session() and smb2 operations()

If there is ->PreviousSessionId field in the session setup request, The session of the previous connection should be destroyed. During this, if the smb2 operation requests in the previous session are being processed, a racy issue could happen with ksmbd_destroy_file_table(). This patch sets conn->status to KSMBD_SESS_NEED_RECONNECT to block incoming operations and waits until on-going operations are complete (i.e. idle) before desctorying the previous session.

Fixes: c8efcc786146 ("ksmbd: add support for durable handles v1/v2") Cc: stable@vger.kernel.org # v6.6+ Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-25040 Signed-off-by: Namjae Jeon linkinjeon@kernel.org Signed-off-by: Steve French stfrench@microsoft.com

diff --git a/fs/smb/server/connection.c b/fs/smb/server/connection.c index 09e1e7771592..7889df8112b4 100644 --- a/fs/smb/server/connection.c +++ b/fs/smb/server/connection.c @@ -165,11 +165,43 @@ void ksmbd_all_conn_set_status(u64 sess_id, u32 status) up_read(&conn_list_lock); }

-void ksmbd_conn_wait_idle(struct ksmbd_conn *conn, u64 sess_id) +void ksmbd_conn_wait_idle(struct ksmbd_conn *conn) { wait_event(conn->req_running_q, atomic_read(&conn->req_running) < 2); }

+int ksmbd_conn_wait_idle_sess_id(struct ksmbd_conn *curr_conn, u64 sess_id) +{

•   struct ksmbd_conn *conn;
  

•   int rc, retry_count = 0, max_timeout = 120;
  

•   int rcount = 1;
  

+retry_idle:

•   if (retry_count >= max_timeout)
  

•           return -EIO;
  

•   down_read(&conn_list_lock);
  

•   list_for_each_entry(conn, &conn_list, conns_list) {
  

•           if (conn->binding || xa_load(&conn->sessions, sess_id)) {
  

•                   if (conn == curr_conn)
  

•                           rcount = 2;
  

•                   if (atomic_read(&conn->req_running) >= rcount) {
  

•                           rc = wait_event_timeout(conn->req_running_q,
  

•                                   atomic_read(&conn->req_running) < rcount,
  

•                                   HZ);
  

•                           if (!rc) {
  

•                                   up_read(&conn_list_lock);
  

•                                   retry_count++;
  

•                                   goto retry_idle;
  

•                           }
  

•                   }
  

•           }
  

•   }
  

•   up_read(&conn_list_lock);
  

•   return 0;
  

+}

int ksmbd_conn_write(struct ksmbd_work *work) { struct ksmbd_conn *conn = work->conn; diff --git a/fs/smb/server/connection.h b/fs/smb/server/connection.h index 5c2845e47cf2..5b947175c048 100644 --- a/fs/smb/server/connection.h +++ b/fs/smb/server/connection.h @@ -145,7 +145,8 @@ extern struct list_head conn_list; extern struct rw_semaphore conn_list_lock;

bool ksmbd_conn_alive(struct ksmbd_conn *conn); -void ksmbd_conn_wait_idle(struct ksmbd_conn *conn, u64 sess_id); +void ksmbd_conn_wait_idle(struct ksmbd_conn *conn); +int ksmbd_conn_wait_idle_sess_id(struct ksmbd_conn *curr_conn, u64 sess_id); struct ksmbd_conn *ksmbd_conn_alloc(void); void ksmbd_conn_free(struct ksmbd_conn *conn); bool ksmbd_conn_lookup_dialect(struct ksmbd_conn *c); diff --git a/fs/smb/server/mgmt/user_session.c b/fs/smb/server/mgmt/user_session.c index 162a12685d2c..99416ce9f501 100644 --- a/fs/smb/server/mgmt/user_session.c +++ b/fs/smb/server/mgmt/user_session.c @@ -311,6 +311,7 @@ void destroy_previous_session(struct ksmbd_conn *conn, { struct ksmbd_session *prev_sess; struct ksmbd_user *prev_user;

•   int err;
  
    down_write(&sessions_table_lock);
    down_write(&conn->session_lock);
  

@@ -325,8 +326,16 @@ void destroy_previous_session(struct ksmbd_conn *conn, memcmp(user->passkey, prev_user->passkey, user->passkey_sz)) goto out;

•   ksmbd_all_conn_set_status(id, KSMBD_SESS_NEED_RECONNECT);
  

•   err = ksmbd_conn_wait_idle_sess_id(conn, id);
  

•   if (err) {
  

•           ksmbd_all_conn_set_status(id, KSMBD_SESS_NEED_NEGOTIATE);
  

•           goto out;
  

•   }
  

•   ksmbd_destroy_file_table(&prev_sess->file_table);
    prev_sess->state = SMB2_SESSION_EXPIRED;
  

•   ksmbd_all_conn_set_status(id, KSMBD_SESS_NEED_NEGOTIATE);
    ksmbd_launch_ksmbd_durable_scavenger();
  

out: up_write(&conn->session_lock); diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index 3f4c56a10a86..cb7f487c96af 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -2213,7 +2213,7 @@ int smb2_session_logoff(struct ksmbd_work *work) ksmbd_conn_unlock(conn);

    ksmbd_close_session_fds(work);

•   ksmbd_conn_wait_idle(conn, sess_id);
  

•   ksmbd_conn_wait_idle(conn);
  
    /*
     * Re-lookup session to validate if session is deleted