6.1-stable review patch. If anyone has any objections, please let me know.
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From: Namjae Jeon linkinjeon@kernel.org
[ Upstream commit b39a1833cc4a2755b02603eec3a71a85e9dff926 ]
Under high concurrency, A tree-connection object (tcon) is freed on a disconnect path while another path still holds a reference and later executes *_put()/write on it.
Reported-by: Qianchang Zhao pioooooooooip@gmail.com Reported-by: Zhitong Liu liuzhitong1993@gmail.com Signed-off-by: Namjae Jeon linkinjeon@kernel.org Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/smb/server/mgmt/tree_connect.c | 18 ++++-------------- fs/smb/server/mgmt/tree_connect.h | 1 - fs/smb/server/smb2pdu.c | 3 --- 3 files changed, 4 insertions(+), 18 deletions(-)
diff --git a/fs/smb/server/mgmt/tree_connect.c b/fs/smb/server/mgmt/tree_connect.c index 94a52a75014a4..9bde1b58f9c46 100644 --- a/fs/smb/server/mgmt/tree_connect.c +++ b/fs/smb/server/mgmt/tree_connect.c @@ -77,7 +77,6 @@ ksmbd_tree_conn_connect(struct ksmbd_work *work, const char *share_name) tree_conn->t_state = TREE_NEW; status.tree_conn = tree_conn; atomic_set(&tree_conn->refcount, 1); - init_waitqueue_head(&tree_conn->refcount_q);
ret = xa_err(xa_store(&sess->tree_conns, tree_conn->id, tree_conn, GFP_KERNEL)); @@ -99,14 +98,8 @@ ksmbd_tree_conn_connect(struct ksmbd_work *work, const char *share_name)
void ksmbd_tree_connect_put(struct ksmbd_tree_connect *tcon) { - /* - * Checking waitqueue to releasing tree connect on - * tree disconnect. waitqueue_active is safe because it - * uses atomic operation for condition. - */ - if (!atomic_dec_return(&tcon->refcount) && - waitqueue_active(&tcon->refcount_q)) - wake_up(&tcon->refcount_q); + if (atomic_dec_and_test(&tcon->refcount)) + kfree(tcon); }
int ksmbd_tree_conn_disconnect(struct ksmbd_session *sess, @@ -118,14 +111,11 @@ int ksmbd_tree_conn_disconnect(struct ksmbd_session *sess, xa_erase(&sess->tree_conns, tree_conn->id); write_unlock(&sess->tree_conns_lock);
- if (!atomic_dec_and_test(&tree_conn->refcount)) - wait_event(tree_conn->refcount_q, - atomic_read(&tree_conn->refcount) == 0); - ret = ksmbd_ipc_tree_disconnect_request(sess->id, tree_conn->id); ksmbd_release_tree_conn_id(sess, tree_conn->id); ksmbd_share_config_put(tree_conn->share_conf); - kfree(tree_conn); + if (atomic_dec_and_test(&tree_conn->refcount)) + kfree(tree_conn); return ret; }
diff --git a/fs/smb/server/mgmt/tree_connect.h b/fs/smb/server/mgmt/tree_connect.h index a42cdd0510411..f0023d86716f2 100644 --- a/fs/smb/server/mgmt/tree_connect.h +++ b/fs/smb/server/mgmt/tree_connect.h @@ -33,7 +33,6 @@ struct ksmbd_tree_connect { int maximal_access; bool posix_extensions; atomic_t refcount; - wait_queue_head_t refcount_q; unsigned int t_state; };
diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index c50dbbfc4cd62..fe3d3d766719a 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -2181,7 +2181,6 @@ int smb2_tree_disconnect(struct ksmbd_work *work) goto err_out; }
- WARN_ON_ONCE(atomic_dec_and_test(&tcon->refcount)); tcon->t_state = TREE_DISCONNECTED; write_unlock(&sess->tree_conns_lock);
@@ -2191,8 +2190,6 @@ int smb2_tree_disconnect(struct ksmbd_work *work) goto err_out; }
- work->tcon = NULL; - rsp->StructureSize = cpu_to_le16(4); err = ksmbd_iov_pin_rsp(work, rsp, sizeof(struct smb2_tree_disconnect_rsp));