FAILED: patch "[PATCH] ksmbd: fix slab-use-after-free in ksmbd_smb2_session_create" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.15-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>.

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-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 0a77715db22611df50b178374c51e2ba0d58866e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024110929-darwinism-jailbird-48ab@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

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

From 0a77715db22611df50b178374c51e2ba0d58866e Mon Sep 17 00:00:00 2001
From: Namjae Jeon <linkinjeon@kernel.org>
Date: Sat, 2 Nov 2024 18:46:38 +0900
Subject: [PATCH] ksmbd: fix slab-use-after-free in ksmbd_smb2_session_create

There is a race condition between ksmbd_smb2_session_create and
ksmbd_expire_session. This patch add missing sessions_table_lock
while adding/deleting session from global session table.

Cc: stable@vger.kernel.org # v5.15+
Reported-by: Norbert Szetei <norbert@doyensec.com>
Tested-by: Norbert Szetei <norbert@doyensec.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/server/mgmt/user_session.c b/fs/smb/server/mgmt/user_session.c
index 9756a4bbfe54..ad02fe555fda 100644
--- a/fs/smb/server/mgmt/user_session.c
+++ b/fs/smb/server/mgmt/user_session.c
@@ -178,6 +178,7 @@ static void ksmbd_expire_session(struct ksmbd_conn *conn)
 	unsigned long id;
 	struct ksmbd_session *sess;
 
+	down_write(&sessions_table_lock);
 	down_write(&conn->session_lock);
 	xa_for_each(&conn->sessions, id, sess) {
 		if (atomic_read(&sess->refcnt) == 0 &&
@@ -191,6 +192,7 @@ static void ksmbd_expire_session(struct ksmbd_conn *conn)
 		}
 	}
 	up_write(&conn->session_lock);
+	up_write(&sessions_table_lock);
 }
 
 int ksmbd_session_register(struct ksmbd_conn *conn,
@@ -232,7 +234,6 @@ void ksmbd_sessions_deregister(struct ksmbd_conn *conn)
 			}
 		}
 	}
-	up_write(&sessions_table_lock);
 
 	down_write(&conn->session_lock);
 	xa_for_each(&conn->sessions, id, sess) {
@@ -252,6 +253,7 @@ void ksmbd_sessions_deregister(struct ksmbd_conn *conn)
 		}
 	}
 	up_write(&conn->session_lock);
+	up_write(&sessions_table_lock);
 }
 
 struct ksmbd_session *ksmbd_session_lookup(struct ksmbd_conn *conn,