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 940EA1A680C; Mon, 13 Apr 2026 16:42:46 +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=1776098566; cv=none; b=hZIjB1ezXJi6RLqPey009+NOZYchJHgCITD/i8tmzUys6rRC9B9XpOsbLJON53/3P76e61Fsj9tNOKi6Y2F0VOI/xqZdGDDG0QOT6tOZMSUIky6126d9Bk/JdbqOTUNbYjhGyVoG0yTz4ulgViCDs03robulNyA+IzIvNHbmQeE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776098566; c=relaxed/simple; bh=tv8aUGFMaN79fIks6eu1pl44L6icBSDx7JuQCyej5kE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=i46sof7WdAjGwogiw5kRngFAQk26YESa9F6xn18aGCjxPrkEBVydFZ4Kf9I7h8GBdQy+7Eo5p+i7BAfuDCY2Hxd0kZg5voD1yH3zjEQ2NSST3j/sc8B/ZuM7cyy4AfBT10zkkE/jJecGfCapkUh5SMFXXNbZbT2Cx3jSieBATRo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=zWcIYCtd; 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="zWcIYCtd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2B1CBC2BCAF; Mon, 13 Apr 2026 16:42:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776098566; bh=tv8aUGFMaN79fIks6eu1pl44L6icBSDx7JuQCyej5kE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zWcIYCtd+wRoXiV/821n5x5WoRp7BSzd+lwHhYPvM6tFRGheF9vcc5MtWLCOUkrAW TteFbYGMBtHgG4jPcogop4DXGCzJWnTxRog8Wo9DzHUpjJviC0els6x5pup987CnNx f1r7q0vOYAVVt+oSL24+5ukaStbaBfsaqhFuue0c= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Kuen-Han Tsai , Sasha Levin Subject: [PATCH 5.15 547/570] usb: gadget: u_ether: Fix race between gether_disconnect and eth_stop Date: Mon, 13 Apr 2026 18:01:18 +0200 Message-ID: <20260413155850.937488713@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260413155830.386096114@linuxfoundation.org> References: <20260413155830.386096114@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuen-Han Tsai [ Upstream commit e1eabb072c75681f78312c484ccfffb7430f206e ] A race condition between gether_disconnect() and eth_stop() leads to a NULL pointer dereference. Specifically, if eth_stop() is triggered concurrently while gether_disconnect() is tearing down the endpoints, eth_stop() attempts to access the cleared endpoint descriptor, causing the following NPE: Unable to handle kernel NULL pointer dereference Call trace: __dwc3_gadget_ep_enable+0x60/0x788 dwc3_gadget_ep_enable+0x70/0xe4 usb_ep_enable+0x60/0x15c eth_stop+0xb8/0x108 Because eth_stop() crashes while holding the dev->lock, the thread running gether_disconnect() fails to acquire the same lock and spins forever, resulting in a hardlockup: Core - Debugging Information for Hardlockup core(7) Call trace: queued_spin_lock_slowpath+0x94/0x488 _raw_spin_lock+0x64/0x6c gether_disconnect+0x19c/0x1e8 ncm_set_alt+0x68/0x1a0 composite_setup+0x6a0/0xc50 The root cause is that the clearing of dev->port_usb in gether_disconnect() is delayed until the end of the function. Move the clearing of dev->port_usb to the very beginning of gether_disconnect() while holding dev->lock. This cuts off the link immediately, ensuring eth_stop() will see dev->port_usb as NULL and safely bail out. Fixes: 2b3d942c4878 ("usb ethernet gadget: split out network core") Cc: stable Signed-off-by: Kuen-Han Tsai Link: https://patch.msgid.link/20260311-gether-disconnect-npe-v1-1-454966adf7c7@google.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/u_ether.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/drivers/usb/gadget/function/u_ether.c +++ b/drivers/usb/gadget/function/u_ether.c @@ -1173,6 +1173,10 @@ void gether_disconnect(struct gether *li DBG(dev, "%s\n", __func__); + spin_lock(&dev->lock); + dev->port_usb = NULL; + spin_unlock(&dev->lock); + netif_stop_queue(dev->net); netif_carrier_off(dev->net); @@ -1210,10 +1214,6 @@ void gether_disconnect(struct gether *li dev->header_len = 0; dev->unwrap = NULL; dev->wrap = NULL; - - spin_lock(&dev->lock); - dev->port_usb = NULL; - spin_unlock(&dev->lock); } EXPORT_SYMBOL_GPL(gether_disconnect);