From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793210400; b=2clOFmgXECMlVvbrWE5In9IU40kZkP3qR6z0bgg0T/G/J5aqjx0dqgU8vrgg598nKsOp sUk6P9Ld5sW5er/37q+pTLKsw2ClYXQRY1S6XKM1Lsy/CPfryogUhRge3bC5A7Roo7+i3 yPK7MwXvCCl7P4TBPBsT5MzifxU88I4rq6GFwFCIdR+PR9I3Zrxv7sI9h+g9L0p4JW+VD 48PqT5+B4mhy53HU1RRVW76jY9SXwiA71Wr45B/nzNAfwaG84qhKKF0h2NqpkXrdqCM2v lt9IOSNyrW7fI4CKV1VMNNGaReX2WxHeJ57UvI1cdHLbQzAdL30Ia2EAMwy5bqZiZpA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793210400; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=TvhcA9HnEPkVOIoohE1Pg1OcTPvwHkGsBA9Si2n8IDY=; b=Ctjsf13U7+s61ykolQCXY+QMp+H10+2ao/nqhaNhNK0NcCfniD5lFq9O+1kjWQkZGuCI vJbbwAZpVO9xzFPo43J00JR4dj78euN98qAmZ3nD5nCk7oVIe7r7Zjv+Gv6o8tnukdzjt 5/ayscxrVay6LJ4G/ZRcxcUopm2Q5iYG1Hw9lHUJzb/W3SCN9xABZj8yO8lGYbd5LS9jS pWp9BWqepLHrbRhxet02QMdXiXDpN0ogzFY4Rhr+ulDT1I6omofIPU3IgaBzJcYdvVjHw YxQDvWV/iTI/0fNuD5W8M4TRb6oVCqG/SO78/TSN8AZ3XcBIr4O3VD2ExVL0yNHmi0w== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=b0G0OBmn; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7519E606A31A; Wed, 28 Oct 2026 18:00:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=b0G0OBmn Received: by smtp.kernel.org (Postfix) with ESMTPSA id C31251F01825; Wed, 28 Oct 2026 17:59:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793210400; bh=TvhcA9HnEPkVOIoohE1Pg1OcTPvwHkGsBA9Si2n8IDY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=b0G0OBmnBhRJy6rZvEOQ0lMcZ7dWYDm1lLi8sn0MAHFj8XUUtjEEgKgPm83VbqC4/ eflz8pCua2lHyuckixVTfGkp7K1V9oXHPPM6gPErEwwPOgiHS45wysr/ApDOwicOb2 4SoHhgOLbEIOwnfQJkqn5FG/+bTTcVKXWWE4E3u8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Fan Wu , Ping-Ke Shih , Sasha Levin Subject: [PATCH 5.15 014/571] wifi: rtl8xxxu: fix use-after-free from rx_urb_wq on stop Date: Wed, 28 Oct 2026 17:52:41 +0100 Message-ID: <20261028170008.359643119@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170008.009143722@linuxfoundation.org> References: <20261028170008.009143722@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Fan Wu [ Upstream commit 6c080026ecc17eecb103f8927c64ea73a74bb818 ] rtl8xxxu arms rx_urb_wq from the RX completion path: rtl8xxxu_rx_complete() hands the URB to rtl8xxxu_queue_rx_urb(), which queues it on rx_urb_pending_list and, once the list grows past RTL8XXXU_RX_URB_PENDING_WATER, schedules rx_urb_wq. The worker rtl8xxxu_rx_urb_work() drains rx_urb_pending_list, recovers priv through container_of, and resubmits each URB through rtl8xxxu_submit_rx_urb(), which anchors it on rx_anchor and dereferences priv->udev. rtl8xxxu_stop() cancels the sibling work items (c2hcmd_work, ra_watchdog, update_beacon_work) but never cancels rx_urb_wq, so a worker armed during the last burst of RX traffic can run rtl8xxxu_rx_urb_work() after rtl8xxxu_disconnect() has called ieee80211_free_hw(), which frees priv, producing a use-after-free. The window opens under active RX traffic (pending count above the watermark) followed by a disconnect. There are two teardown races to close: * rtl8xxxu_queue_rx_urb() decided whether to enqueue under rx_urb_lock but called schedule_work() after dropping the lock. A completion that observed shutdown == false and released the lock could then call schedule_work() after rtl8xxxu_stop() had set shutdown and cancel_work_sync() had already returned, arming the worker to run after the teardown. Move schedule_work() under the same !shutdown branch so the arming decision is atomic with the shutdown check. * rtl8xxxu_rx_urb_work() anchors every URB it drained back onto rx_anchor through rtl8xxxu_submit_rx_urb(). A worker still running when usb_kill_anchored_urbs(&priv->rx_anchor) returned would submit a URB that escaped the kill. In rtl8xxxu_stop(), call cancel_work_sync(&priv->rx_urb_wq) before the kill so the worker is drained first. After priv->shutdown is set under rx_urb_lock, completions can no longer queue rx_urb_wq. cancel_work_sync() then drains the last queued or running worker, and the following usb_kill_anchored_urbs() kills the URBs it may have submitted. rtl8xxxu_disconnect() is covered because ieee80211_unregister_hw() guarantees .stop() runs for a live interface before ieee80211_free_hw() frees priv. The probe error path needs no cancel: rx_urb_wq is INIT_WORK()'d there but cannot have been scheduled, since no URB is submitted before ieee80211_register_hw() succeeds. This bug was found by static analysis. Fixes: 26f1fad29ad9 ("New driver: rtl8xxxu (mac80211)") Cc: stable@vger.kernel.org Signed-off-by: Fan Wu Signed-off-by: Ping-Ke Shih Link: https://patch.msgid.link/20260630033117.3377-1-fanwu01@zju.edu.cn Signed-off-by: Sasha Levin --- .../wireless/realtek/rtl8xxxu/rtl8xxxu_core.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c index 9bcc137da20f8..526491b1ec082 100644 --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c @@ -5171,14 +5171,19 @@ static void rtl8xxxu_queue_rx_urb(struct rtl8xxxu_priv *priv, { struct sk_buff *skb; unsigned long flags; - int pending = 0; spin_lock_irqsave(&priv->rx_urb_lock, flags); if (!priv->shutdown) { list_add_tail(&rx_urb->list, &priv->rx_urb_pending_list); priv->rx_urb_pending_count++; - pending = priv->rx_urb_pending_count; + /* + * Arm the worker under rx_urb_lock so this is atomic with the + * shutdown check: moving it out of the lock would let a + * completion arm the work after rtl8xxxu_stop() canceled it. + */ + if (priv->rx_urb_pending_count > RTL8XXXU_RX_URB_PENDING_WATER) + schedule_work(&priv->rx_urb_wq); } else { skb = (struct sk_buff *)rx_urb->urb.context; dev_kfree_skb_irq(skb); @@ -5186,9 +5191,6 @@ static void rtl8xxxu_queue_rx_urb(struct rtl8xxxu_priv *priv, } spin_unlock_irqrestore(&priv->rx_urb_lock, flags); - - if (pending > RTL8XXXU_RX_URB_PENDING_WATER) - schedule_work(&priv->rx_urb_wq); } static void rtl8xxxu_rx_urb_work(struct work_struct *work) @@ -6465,6 +6467,13 @@ static void rtl8xxxu_stop(struct ieee80211_hw *hw) priv->shutdown = true; spin_unlock_irqrestore(&priv->rx_urb_lock, flags); + /* + * Cancel before killing rx_anchor: the worker re-anchors every URB + * it drained via rtl8xxxu_submit_rx_urb(), so a worker still running + * after the kill could submit a URB that escapes it. + */ + cancel_work_sync(&priv->rx_urb_wq); + usb_kill_anchored_urbs(&priv->rx_anchor); usb_kill_anchored_urbs(&priv->tx_anchor); if (priv->usb_interrupts) -- 2.53.0