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 33b235a6e6ebe0f05f3586a71e8d281d00f71e2e # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023100844-woof-habitable-c11f@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

33b235a6e6eb ("ksmbd: fix race condition between tree conn lookup and disconnect") e2b76ab8b5c9 ("ksmbd: add support for read compound") e202a1e8634b ("ksmbd: no response from compound read") 7b7d709ef7cf ("ksmbd: add missing compound request handing in some commands") 81a94b27847f ("ksmbd: use kvzalloc instead of kvmalloc") 38c8a9a52082 ("smb: move client and server files to common directory fs/smb") 30210947a343 ("ksmbd: fix racy issue under cocurrent smb2 tree disconnect") abcc506a9a71 ("ksmbd: fix racy issue from smb2 close and logoff with multichannel") ea174a918939 ("ksmbd: destroy expired sessions") f5c779b7ddbd ("ksmbd: fix racy issue from session setup and logoff") 74d7970febf7 ("ksmbd: fix racy issue from using ->d_parent and ->d_name") 34e8ccf9ce24 ("ksmbd: set NegotiateContextCount once instead of every inc") 42bc6793e452 ("Merge tag 'pull-lock_rename_child' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs into ksmbd-for-next")

thanks,

greg k-h

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

From 33b235a6e6ebe0f05f3586a71e8d281d00f71e2e Mon Sep 17 00:00:00 2001 From: Namjae Jeon linkinjeon@kernel.org Date: Thu, 5 Oct 2023 11:22:03 +0900 Subject: [PATCH] ksmbd: fix race condition between tree conn lookup and disconnect

if thread A in smb2_write is using work-tcon, other thread B use smb2_tree_disconnect free the tcon, then thread A will use free'd tcon.

Time + Thread A | Thread A smb2_write | smb2_tree_disconnect | | | kfree(tree_conn) | // UAF! | work->tcon->share_conf | +

This patch add state, reference count and lock for tree conn to fix race condition issue.

Reported-by: luosili rootlab@huawei.com Signed-off-by: Namjae Jeon linkinjeon@kernel.org Signed-off-by: Steve French stfrench@microsoft.com

diff --git a/fs/smb/server/mgmt/tree_connect.c b/fs/smb/server/mgmt/tree_connect.c index 408cddf2f094..d2c81a8a11dd 100644 --- a/fs/smb/server/mgmt/tree_connect.c +++ b/fs/smb/server/mgmt/tree_connect.c @@ -73,7 +73,10 @@ ksmbd_tree_conn_connect(struct ksmbd_conn *conn, struct ksmbd_session *sess,

tree_conn->user = sess->user; tree_conn->share_conf = sc; + 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)); @@ -93,14 +96,33 @@ ksmbd_tree_conn_connect(struct ksmbd_conn *conn, struct ksmbd_session *sess, return status; }

+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); +} + int ksmbd_tree_conn_disconnect(struct ksmbd_session *sess, struct ksmbd_tree_connect *tree_conn) { int ret;

+ write_lock(&sess->tree_conns_lock); + 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); - xa_erase(&sess->tree_conns, tree_conn->id); ksmbd_share_config_put(tree_conn->share_conf); kfree(tree_conn); return ret; @@ -111,11 +133,15 @@ struct ksmbd_tree_connect *ksmbd_tree_conn_lookup(struct ksmbd_session *sess, { struct ksmbd_tree_connect *tcon;

+ read_lock(&sess->tree_conns_lock); tcon = xa_load(&sess->tree_conns, id); if (tcon) { - if (test_bit(TREE_CONN_EXPIRE, &tcon->status)) + if (tcon->t_state != TREE_CONNECTED) + tcon = NULL; + else if (!atomic_inc_not_zero(&tcon->refcount)) tcon = NULL; } + read_unlock(&sess->tree_conns_lock);

return tcon; } @@ -129,8 +155,18 @@ int ksmbd_tree_conn_session_logoff(struct ksmbd_session *sess) if (!sess) return -EINVAL;

- xa_for_each(&sess->tree_conns, id, tc) + xa_for_each(&sess->tree_conns, id, tc) { + write_lock(&sess->tree_conns_lock); + if (tc->t_state == TREE_DISCONNECTED) { + write_unlock(&sess->tree_conns_lock); + ret = -ENOENT; + continue; + } + tc->t_state = TREE_DISCONNECTED; + write_unlock(&sess->tree_conns_lock); + ret |= ksmbd_tree_conn_disconnect(sess, tc); + } xa_destroy(&sess->tree_conns); return ret; } diff --git a/fs/smb/server/mgmt/tree_connect.h b/fs/smb/server/mgmt/tree_connect.h index 562d647ad9fa..6377a70b811c 100644 --- a/fs/smb/server/mgmt/tree_connect.h +++ b/fs/smb/server/mgmt/tree_connect.h @@ -14,7 +14,11 @@ struct ksmbd_share_config; struct ksmbd_user; struct ksmbd_conn;

-#define TREE_CONN_EXPIRE 1 +enum { + TREE_NEW = 0, + TREE_CONNECTED, + TREE_DISCONNECTED +};

struct ksmbd_tree_connect { int id; @@ -27,7 +31,9 @@ struct ksmbd_tree_connect {

int maximal_access; bool posix_extensions; - unsigned long status; + atomic_t refcount; + wait_queue_head_t refcount_q; + unsigned int t_state; };

struct ksmbd_tree_conn_status { @@ -46,6 +52,7 @@ struct ksmbd_session; struct ksmbd_tree_conn_status ksmbd_tree_conn_connect(struct ksmbd_conn *conn, struct ksmbd_session *sess, const char *share_name); +void ksmbd_tree_connect_put(struct ksmbd_tree_connect *tcon);

int ksmbd_tree_conn_disconnect(struct ksmbd_session *sess, struct ksmbd_tree_connect *tree_conn); diff --git a/fs/smb/server/mgmt/user_session.c b/fs/smb/server/mgmt/user_session.c index b8be14a96cf6..15f68ee05089 100644 --- a/fs/smb/server/mgmt/user_session.c +++ b/fs/smb/server/mgmt/user_session.c @@ -355,6 +355,7 @@ static struct ksmbd_session *__session_create(int protocol) xa_init(&sess->ksmbd_chann_list); xa_init(&sess->rpc_handle_list); sess->sequence_number = 1; + rwlock_init(&sess->tree_conns_lock);

ret = __init_smb2_session(sess); if (ret) diff --git a/fs/smb/server/mgmt/user_session.h b/fs/smb/server/mgmt/user_session.h index f99d475b28db..63cb08fffde8 100644 --- a/fs/smb/server/mgmt/user_session.h +++ b/fs/smb/server/mgmt/user_session.h @@ -60,6 +60,7 @@ struct ksmbd_session {

struct ksmbd_file_table file_table; unsigned long last_active; + rwlock_t tree_conns_lock; };

static inline int test_session_flag(struct ksmbd_session *sess, int bit) diff --git a/fs/smb/server/server.c b/fs/smb/server/server.c index 32347fec33c4..3079e607c5fe 100644 --- a/fs/smb/server/server.c +++ b/fs/smb/server/server.c @@ -241,6 +241,8 @@ static void __handle_ksmbd_work(struct ksmbd_work *work, } while (is_chained == true);

send: + if (work->tcon) + ksmbd_tree_connect_put(work->tcon); smb3_preauth_hash_rsp(work); if (work->sess && work->sess->enc && work->encrypted && conn->ops->encrypt_resp) { diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index fd6f05786ac2..898860adf929 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -1993,6 +1993,9 @@ int smb2_tree_connect(struct ksmbd_work *work) if (conn->posix_ext_supported) status.tree_conn->posix_extensions = true;

+ write_lock(&sess->tree_conns_lock); + status.tree_conn->t_state = TREE_CONNECTED; + write_unlock(&sess->tree_conns_lock); rsp->StructureSize = cpu_to_le16(16); out_err1: rsp->Capabilities = 0; @@ -2122,27 +2125,50 @@ int smb2_tree_disconnect(struct ksmbd_work *work)

ksmbd_debug(SMB, "request\n");

+ if (!tcon) { + ksmbd_debug(SMB, "Invalid tid %d\n", req->hdr.Id.SyncId.TreeId); + + rsp->hdr.Status = STATUS_NETWORK_NAME_DELETED; + err = -ENOENT; + goto err_out; + } + + ksmbd_close_tree_conn_fds(work); + + write_lock(&sess->tree_conns_lock); + if (tcon->t_state == TREE_DISCONNECTED) { + write_unlock(&sess->tree_conns_lock); + rsp->hdr.Status = STATUS_NETWORK_NAME_DELETED; + err = -ENOENT; + goto err_out; + } + + WARN_ON_ONCE(atomic_dec_and_test(&tcon->refcount)); + tcon->t_state = TREE_DISCONNECTED; + write_unlock(&sess->tree_conns_lock); + + err = ksmbd_tree_conn_disconnect(sess, tcon); + if (err) { + rsp->hdr.Status = STATUS_NETWORK_NAME_DELETED; + 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)); if (err) { rsp->hdr.Status = STATUS_INSUFFICIENT_RESOURCES; - smb2_set_err_rsp(work); - return err; + goto err_out; }

- if (!tcon || test_and_set_bit(TREE_CONN_EXPIRE, &tcon->status)) { - ksmbd_debug(SMB, "Invalid tid %d\n", req->hdr.Id.SyncId.TreeId); + return 0;

- rsp->hdr.Status = STATUS_NETWORK_NAME_DELETED; - smb2_set_err_rsp(work); - return -ENOENT; - } +err_out: + smb2_set_err_rsp(work); + return err;

- ksmbd_close_tree_conn_fds(work); - ksmbd_tree_conn_disconnect(sess, tcon); - work->tcon = NULL; - return 0; }

/**