Patch "ksmbd: fix use-after-free in ksmbd_session_rpc_open" has been added to the 6.1-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    ksmbd: fix use-after-free in ksmbd_session_rpc_open

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ksmbd-fix-use-after-free-in-ksmbd_session_rpc_open.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From 1468888505@139.com Mon Feb  2 04:15:55 2026
From: Li hongliang <1468888505@139.com>
Date: Mon,  2 Feb 2026 11:15:50 +0800
Subject: ksmbd: fix use-after-free in ksmbd_session_rpc_open
To: gregkh@linuxfoundation.org, stable@vger.kernel.org, linkinjeon@kernel.org
Cc: patches@lists.linux.dev, linux-kernel@vger.kernel.org, norbert@doyensec.com, ysk@kzalloc.com, sfrench@samba.org, senozhatsky@chromium.org, tom@talpey.com, akendo@akendo.eu, set_pte_at@outlook.com, linux-cifs@vger.kernel.org, stfrench@microsoft.com
Message-ID: <20260202031550.514894-1-1468888505@139.com>

From: Namjae Jeon <linkinjeon@kernel.org>

[ Upstream commit a1f46c99d9ea411f9bf30025b912d881d36fc709 ]

A UAF issue can occur due to a race condition between
ksmbd_session_rpc_open() and __session_rpc_close().
Add rpc_lock to the session to protect it.

Cc: stable@vger.kernel.org
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>
[ KSMBD_DEFAULT_GFP is introduced by commit 0066f623bce8 ("ksmbd: use __GFP_RETRY_MAYFAIL")
 after linux-6.13. Here we still use GFP_KERNEL. ]
Signed-off-by: Li hongliang <1468888505@139.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/smb/server/mgmt/user_session.c |   20 ++++++++++++++------
 fs/smb/server/mgmt/user_session.h |    1 +
 2 files changed, 15 insertions(+), 6 deletions(-)

--- a/fs/smb/server/mgmt/user_session.c
+++ b/fs/smb/server/mgmt/user_session.c
@@ -59,10 +59,12 @@ static void ksmbd_session_rpc_clear_list
 	struct ksmbd_session_rpc *entry;
 	long index;
 
+	down_write(&sess->rpc_lock);
 	xa_for_each(&sess->rpc_handle_list, index, entry) {
 		xa_erase(&sess->rpc_handle_list, index);
 		__session_rpc_close(sess, entry);
 	}
+	up_write(&sess->rpc_lock);
 
 	xa_destroy(&sess->rpc_handle_list);
 }
@@ -92,7 +94,7 @@ int ksmbd_session_rpc_open(struct ksmbd_
 {
 	struct ksmbd_session_rpc *entry, *old;
 	struct ksmbd_rpc_command *resp;
-	int method;
+	int method, id;
 
 	method = __rpc_method(rpc_name);
 	if (!method)
@@ -102,26 +104,29 @@ int ksmbd_session_rpc_open(struct ksmbd_
 	if (!entry)
 		return -ENOMEM;
 
+	down_read(&sess->rpc_lock);
 	entry->method = method;
-	entry->id = ksmbd_ipc_id_alloc();
-	if (entry->id < 0)
+	entry->id = id = ksmbd_ipc_id_alloc();
+	if (id < 0)
 		goto free_entry;
-	old = xa_store(&sess->rpc_handle_list, entry->id, entry, GFP_KERNEL);
+	old = xa_store(&sess->rpc_handle_list, id, entry, GFP_KERNEL);
 	if (xa_is_err(old))
 		goto free_id;
 
-	resp = ksmbd_rpc_open(sess, entry->id);
+	resp = ksmbd_rpc_open(sess, id);
 	if (!resp)
 		goto erase_xa;
 
+	up_read(&sess->rpc_lock);
 	kvfree(resp);
-	return entry->id;
+	return id;
 erase_xa:
 	xa_erase(&sess->rpc_handle_list, entry->id);
 free_id:
 	ksmbd_rpc_id_free(entry->id);
 free_entry:
 	kfree(entry);
+	up_read(&sess->rpc_lock);
 	return -EINVAL;
 }
 
@@ -129,9 +134,11 @@ void ksmbd_session_rpc_close(struct ksmb
 {
 	struct ksmbd_session_rpc *entry;
 
+	down_write(&sess->rpc_lock);
 	entry = xa_erase(&sess->rpc_handle_list, id);
 	if (entry)
 		__session_rpc_close(sess, entry);
+	up_write(&sess->rpc_lock);
 }
 
 int ksmbd_session_rpc_method(struct ksmbd_session *sess, int id)
@@ -404,6 +411,7 @@ static struct ksmbd_session *__session_c
 	sess->sequence_number = 1;
 	rwlock_init(&sess->tree_conns_lock);
 	atomic_set(&sess->refcnt, 2);
+	init_rwsem(&sess->rpc_lock);
 
 	ret = __init_smb2_session(sess);
 	if (ret)
--- a/fs/smb/server/mgmt/user_session.h
+++ b/fs/smb/server/mgmt/user_session.h
@@ -63,6 +63,7 @@ struct ksmbd_session {
 	rwlock_t			tree_conns_lock;
 
 	atomic_t			refcnt;
+	struct rw_semaphore		rpc_lock;
 };
 
 static inline int test_session_flag(struct ksmbd_session *sess, int bit)


Patches currently in stable-queue which might be from 1468888505@139.com are

queue-6.1/vhost-scsi-fix-handling-of-multiple-calls-to-vhost_scsi_set_endpoint.patch
queue-6.1/fs-ntfs3-initialize-allocated-memory-before-use.patch
queue-6.1/drm-radeon-delete-radeon_fence_process-in-is_signaled-no-deadlock.patch
queue-6.1/ksmbd-fix-race-condition-in-rpc-handle-list-access.patch
queue-6.1/ksmbd-fix-use-after-free-in-ksmbd_session_rpc_open.patch
queue-6.1/drm-amdgpu-replace-mutex-with-spinlock-for-rlcg-register-access-to-avoid-priority-inversion-in-sriov.patch
queue-6.1/sctp-linearize-cloned-gso-packets-in-sctp_rcv.patch