From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 475E85867D4 for ; Wed, 9 Sep 2026 20:46:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788986769; cv=none; b=VMKopQ8zXWBnCYl8GsgswYlv+0vw949lJT4Zz2iHnWimCc2glESfJDoF5McAgppgGEAnUkQVh1H1B0Tv1jRxG/Xs2ARVSDSwfu9843BcB6dpeIGQJD5psL2DlVnAUFozhZFXqZejzJZlkTTCAW5Y7x6n3FUEWPms9KFtf4QTAHM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788986769; c=relaxed/simple; bh=cf4WyZYsSQaC5SjpaW5jaDq4O9i1DRJG8gy2PyMEOUU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=diBYk2U90kLCQwkYAmbOP3ZQz/Hl0jxJvnxkTVLTLD+7PAAY9lNAlgmTWUn68utwrCLaM7lbJe4FrcLbgAzZwkF7xPvbNw6DKfp0EXvglkNxK7daMrD1TxQmPqXcb+q1cBSQKvtAVj+GsezJOkvFe/Q0lrSEIY3ISzszLnH8PBI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jy11atqq; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="jy11atqq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 931671F00893; Wed, 9 Sep 2026 20:45:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788986760; bh=RH1lWvslWtocTYBqGzURy8/HYIaS1Llcl8Ofo2RybjI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=jy11atqqxhnZwOwGW12xsKNlEZKg38xjWRkFMdoz6EbwlLsBoYb4t/et0PopW8aHZ oyCqDX8quEMa8m6yQM0+rNE5SxefLdF4LrlfZQ2kezr6OaQ+10p/FK9rClKohqDXJK 20v7OnK+Hv/VSLSof57Pxo8654NG0yp+HwMR4EC47ugzDLfV8SP2vatLB0VT79mbiO 6K+qi1xSUavZCba6cZXRO1rn6fWjI7U7w38NA/VWWB4JewSn6dM88LYem2XTrFqRqi QmFQHeJnbI/wtpEaWeoCd0rYxVlzTPT4rTiGreg2m/Z3pZVbmtovLQkzD3zLa+D5Qe blqkQRZAOXJnQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Fan Wu , Ping-Ke Shih , Sasha Levin Subject: [PATCH 6.1.y] wifi: rtl8xxxu: fix use-after-free from rx_urb_wq on stop Date: Wed, 9 Sep 2026 16:45:57 -0400 Message-ID: <20260909204558.3679540-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090418-judgingly-easiest-25f4@gregkh> References: <2026090418-judgingly-easiest-25f4@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 c1bc55f0e4c01..20a7537d2cae8 100644 --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c @@ -5263,14 +5263,19 @@ 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); @@ -5278,9 +5283,6 @@ 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) @@ -6529,6 +6531,13 @@ 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