FAILED: patch "[PATCH] smb: client: cancel reconnect work in" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-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 <[email protected]>.

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-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x c65eae6f61d1778ff7a82e4aae4080e26f486af1
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026092201-lethargic-bouncing-9f5e@gregkh' --subject-prefix 'PATCH 5.10.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

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

From c65eae6f61d1778ff7a82e4aae4080e26f486af1 Mon Sep 17 00:00:00 2001
From: Paulo Alcantara <[email protected]>
Date: Fri, 11 Sep 2026 22:38:04 -0300
Subject: [PATCH] smb: client: cancel reconnect work in
clean_demultiplex_info()

clean_demultiplex_info() cancels server->echo delayed work but not server->reconnect, which can cause a use-after-free when the demultiplex thread exits while a reconnect work is still queued:

cifs_demultiplex_thread()

    cifs_readv_from_socket()
      cifs_reconnect()
        __cifs_reconnect()
          cifs_queue_server_reconn()
            mod_delayed_work(cifsiod_wq, &server->reconnect, 0)
    clean_demultiplex_info()
      cancel_delayed_work_sync(&server->echo)   // echo canceled
                                                 // reconnect NOT canceled
      kfree_sensitive(server)                    // server freed

...later, on cifsiod_wq:

smb2_reconnect_server()

    server->srv_count  // UAF read of freed server

Fix this by canceling server->reconnect delayed work in clean_demultiplex_info() before the server is freed, the same way cifs_put_tcp_session() already does.

index b6e98eb31673..bef710d9a3c3 100644
@@ -1067,6 +1067,7 @@ clean_demultiplex_info(struct TCP_Server_Info *server)
 	spin_unlock(&server->srv_lock);
 
 	cancel_delayed_work_sync(&server->echo);
+	cancel_delayed_work_sync(&server->reconnect);
 
 	spin_lock(&server->srv_lock);
 	server->tcpStatus = CifsExiting;

From: Paulo Alcantara <[email protected]>

[ Upstream commit c65eae6f61d1778ff7a82e4aae4080e26f486af1 ]

clean_demultiplex_info() cancels server->echo delayed work but not server->reconnect, which can cause a use-after-free when the demultiplex thread exits while a reconnect work is still queued:

cifs_demultiplex_thread()

    cifs_readv_from_socket()
      cifs_reconnect()
        __cifs_reconnect()
          cifs_queue_server_reconn()
            mod_delayed_work(cifsiod_wq, &server->reconnect, 0)
    clean_demultiplex_info()
      cancel_delayed_work_sync(&server->echo)   // echo canceled
                                                 // reconnect NOT canceled
      kfree_sensitive(server)                    // server freed

...later, on cifsiod_wq:

smb2_reconnect_server()

    server->srv_count  // UAF read of freed server

Fix this by canceling server->reconnect delayed work in clean_demultiplex_info() before the server is freed, the same way cifs_put_tcp_session() already does.

---
 fs/cifs/connect.c | 1 +
 1 file changed, 1 insertion(+)

index a95b9d2318fa2..fc74ac831e197 100644
@@ -890,6 +890,7 @@ static void clean_demultiplex_info(struct TCP_Server_Info *server)
 	spin_unlock(&cifs_tcp_ses_lock);
 
 	cancel_delayed_work_sync(&server->echo);
+	cancel_delayed_work_sync(&server->reconnect);
 
 	spin_lock(&GlobalMid_Lock);
 	server->tcpStatus = CifsExiting;

2.53.0