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 774DF2D12EE for ; Thu, 10 Sep 2026 00:18:11 +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=1788999492; cv=none; b=aYSaPLUH/F/+8eUFxiO9MeyzmNhSoyD2FIQaUNlTMr8uBSJPFrnMPeTKpQwlVEgBqED7LYf6fqul1duvM2jFnCDHtJAXN9nJ9bzK9BU1kksvD22vPm4NYUtgAZPWUOmGu6xv6IDP7xshE5RX8r3/+BTbVnOXjdvT1qDIQt8Wgug= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788999492; c=relaxed/simple; bh=xQ3SOOQILXvBOBnX1DDLw8EWIoJqqW4UZkUbfuuwl8M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mjgEapPVXOq53ipGzbFLPOzWMekijzM/61Z+l38hKM9zIdB3XWUcjm643aR/fSoAU+XukSsJAN/jg+e+XLqe2NBZrnHde89+pHw1Hjo1nfipA/lBbSE/3vpHK+ofAPE6DO9H470HkbEnSkQtVRRVbP2ev9BEA4uq2u43+4bj6mA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Dfq1+/Do; 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="Dfq1+/Do" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CE29D1F00893; Thu, 10 Sep 2026 00:18:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788999491; bh=tLGHCrxpX22oAarGfFEenxAp3+eUvQS1XzhdKMgaezU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Dfq1+/DojXNqF8wo7DtYf2+n0Q2ZkZ+LLz5OyvbgK/fGJf9YA+IRiGm3dFKMx7UqS /5LWt+7n8YfCngIYO4C2GzMe/tmfOY+FBcRFDZwtFHRE2O0hnzeMtxwgwoO4qSJ6lk dgSI0Br+H726GjzcDN7JdS8RCMn7RlH9w1yG4kjFvJiotYSTpDNX6W5v4xzH4y+F24 3bwEG9stdrY3jHzijXjUbriJluwjVIULT1zq5AkPAJ9+XMqeyKQKDxh+akbpAhIxpA gJqbkQefrpYcksANAzsYXFkbE/wxV1dLiBCcXi94Fbx3tuNxFBm4mVufQ9OdXp+eFB JPFptvQkwaFTw== From: Sasha Levin To: stable@vger.kernel.org Cc: Fan Wu , Ping-Ke Shih , Sasha Levin Subject: [PATCH 5.10.y] wifi: rtl8xxxu: fix use-after-free from rx_urb_wq on stop Date: Wed, 9 Sep 2026 20:18:07 -0400 Message-ID: <20260910001807.3749308-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090420-fleshy-punctured-8063@gregkh> References: <2026090420-fleshy-punctured-8063@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 7cf2693619c92..ff161685ad75f 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) @@ -6464,6 +6466,13 @@ 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