From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C66AA347FD0; Tue, 6 Jan 2026 17:18:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767719884; cv=none; b=N+nyqBgY5fbvGS+3Is+Teh6vNkjGOq0o+50hMFFiiza+5I7Pjao5xhhkEZkhWkwb4jKviREqco2etbIAXoyz+W9ps0Yc2MEGAX45fMEvvQ6v3D7EYD4n/dUiJCHX5MNgIF0ASlEs0xLintnxyYrtC/8FzeAotcvTAJqKvYaMqN4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767719884; c=relaxed/simple; bh=dDt7IDTu5F1hqNeCwPp0BATHDU4OavLjJ4O5+H4X3ec=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=O5XzSJvi5DRiNi3pHg+1/eBAtPQY0Ro0a3CeQI+y3CgBnBuTNHd3WUTYfhbbhsAtToEpUgfSvOU89yu+u1RhqyMwgYcDTJD9Bg4SkOiFFXYbkwDK5hkoTi5Cr4TeyaQAAWjE1kON2NchzY+7r6qU96w6pris18SZG9XzMyKv8HY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=XRG/9XW/; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="XRG/9XW/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4CB90C116C6; Tue, 6 Jan 2026 17:18:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1767719884; bh=dDt7IDTu5F1hqNeCwPp0BATHDU4OavLjJ4O5+H4X3ec=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XRG/9XW/OctSGv1Qg10BIEVO0I2qTkn8EQ3jJtrS2yFTqmvhI4k8YTf11C9z5TmX2 m6yTqYTBOvUQGfxSvulv0oUR5ZMiqU/A5Ad8YKkYpflxQAp/S7Wly3BjJ36i2ffi9r oiczLN/eUIwycvQBKCZHaLRMaNSogIvg3NM9u9rU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Qianchang Zhao , Zhitong Liu , Namjae Jeon , Steve French , Sasha Levin Subject: [PATCH 6.12 037/567] ksmbd: fix use-after-free in ksmbd_tree_connect_put under concurrency Date: Tue, 6 Jan 2026 17:56:59 +0100 Message-ID: <20260106170452.712061082@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260106170451.332875001@linuxfoundation.org> References: <20260106170451.332875001@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Namjae Jeon [ 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 Reported-by: Zhitong Liu Signed-off-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Sasha Levin --- 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 ecfc575086712..d3483d9c757c7 100644 --- a/fs/smb/server/mgmt/tree_connect.c +++ b/fs/smb/server/mgmt/tree_connect.c @@ -78,7 +78,6 @@ 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, KSMBD_DEFAULT_GFP)); @@ -100,14 +99,8 @@ 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, @@ -119,14 +112,11 @@ 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 d9e28191c267e..b32df37da70d4 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -2190,7 +2190,6 @@ 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); @@ -2200,8 +2199,6 @@ 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)); -- 2.51.0