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 8C85C3D903D; Wed, 8 Apr 2026 18:39:17 +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=1775673557; cv=none; b=HY+pDt2eaNoTkxOOoISvKJyXFhuhvkZfmM4oVEZsPBWE479NVvWFV6hfm43JG3M39WNjbYSFl24lbS1ZOvr/FocX4T/knIVzpzsBYQ+H4fbojcFYCh7+yxhtnxUGCkPcuLKq3Cwu/S5WNir5pp41sn38aQ7YPseH/KIw6idDAXY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775673557; c=relaxed/simple; bh=Qhckl2taUZlyrU/S4eVWhoEPTacsTAdDL7CnvIBsnT0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=E6N2Ce/LCRE98CE9uJrjlsGW2vpwhdje6MAgpmjUCd7mwm1vheK6hAUWwLwerLDBbOGDfitgoiVGsW37DgRELtyV0HiecZ6gPx38vnUe78VsXSjAuMY+mLi4CtTDQlzdDTfhXTm9NwQzJSPx9iSDVHrg+Fx5vFLJWrhd4SnOl90= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=cVEGVm9K; 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="cVEGVm9K" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1EA4CC19421; Wed, 8 Apr 2026 18:39:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1775673557; bh=Qhckl2taUZlyrU/S4eVWhoEPTacsTAdDL7CnvIBsnT0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cVEGVm9KvIXlEcWCFKm1z0CoYtjrk0dl/w2GZj4jJ1Cm2/jZVovIXCjhRRb3lCX82 b5hnQUygoDceaQsvNmOdeF+Y8nnRRcm7EE+5pthe69lN/xzEU96vO5SDCm/7hMttFe 9wrlpZQrfo7PuaoeeuwMZbCuH8m1MKK4eFx7/d3Q= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Kuen-Han Tsai Subject: [PATCH 6.18 252/277] usb: gadget: u_ether: Fix race between gether_disconnect and eth_stop Date: Wed, 8 Apr 2026 20:03:57 +0200 Message-ID: <20260408175943.269293175@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260408175933.836769063@linuxfoundation.org> References: <20260408175933.836769063@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuen-Han Tsai commit e1eabb072c75681f78312c484ccfffb7430f206e upstream. 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 --- drivers/usb/gadget/function/u_ether.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) --- a/drivers/usb/gadget/function/u_ether.c +++ b/drivers/usb/gadget/function/u_ether.c @@ -1222,6 +1222,11 @@ void gether_disconnect(struct gether *li DBG(dev, "%s\n", __func__); + spin_lock(&dev->lock); + dev->port_usb = NULL; + link->is_suspend = false; + spin_unlock(&dev->lock); + netif_stop_queue(dev->net); netif_carrier_off(dev->net); @@ -1259,11 +1264,6 @@ void gether_disconnect(struct gether *li dev->header_len = 0; dev->unwrap = NULL; dev->wrap = NULL; - - spin_lock(&dev->lock); - dev->port_usb = NULL; - link->is_suspend = false; - spin_unlock(&dev->lock); } EXPORT_SYMBOL_GPL(gether_disconnect);