From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9B817C4338F for ; Fri, 6 Aug 2021 08:12:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6E7E260238 for ; Fri, 6 Aug 2021 08:12:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243305AbhHFINA (ORCPT ); Fri, 6 Aug 2021 04:13:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:43204 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230384AbhHFINA (ORCPT ); Fri, 6 Aug 2021 04:13:00 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3489660238; Fri, 6 Aug 2021 08:12:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1628237563; bh=6ksPby0Roy9tu9p+osT6wamK/zd65frJk2QyzffxK4s=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ptl5NGtJYH14Rc4q+WTR8UFQNOw7H+R8ogPntlA4v/2hnouqksIexSau3qGJiRGFG canUd3Mv/I+BobAfcxrjxLQQl/oE7tHZAzPvYpn64wYQMiwjQlON3SSHOxzvZM304P e+qVYSAgGBEguhXlpOBc6N977j1U0ln2M2CmHHEw= Date: Fri, 6 Aug 2021 10:12:41 +0200 From: Greg Kroah-Hartman To: Daehwan Jung Cc: Felipe Balbi , "open list:USB GADGET/PERIPHERAL SUBSYSTEM" , open list , taehyun cho Subject: Re: usb: gadget: u_serial: check Null pointer in EP callback Message-ID: References: <1628236406-185160-1-git-send-email-dh10.jung@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1628236406-185160-1-git-send-email-dh10.jung@samsung.com> Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Fri, Aug 06, 2021 at 04:53:26PM +0900, Daehwan Jung wrote: > From: taehyun cho > > Endpoint complete function in u_serial can be executed > when 'gs_port' is Null. This situation happens when > 'dwc3_gadget_pullup' returns ETIMEDOUT. The reason why > ETIMEDOUT is returned is that whole system is out of order > including interrupt regardless of USB. > > pc : __lock_acquire+0x54/0x5ec > lr : lock_acquire+0xe8/0x198 > sp : ffffffc03914b9d0 > x29: ffffffc03914b9d0 x28: ffffff895f13b680 > x27: 0000000000000000 x26: 0000000000000000 > x25: 00000000000003c8 x24: 0000000000000080 > x23: ffffffc010a8f650 x22: 0000000000000000 > x21: 0000000000000000 x20: 0000000000000000 > x19: ffffffc010a8f650 x18: ffffffc02d70a0b0 > x17: 0000000000000000 x16: 00000000000229e0 > x15: 0000000000000004 x14: 00000000000004f2 > x13: ffffffc0120fe178 x12: 0000000000000003 > x11: 00000000ffffffff x10: 0000000100000001 > x9 : 0000000000000001 x8 : 00000000000003c8 > x7 : 0000000000000000 x6 : ffffffc010a8f650 > x5 : 0000000000000000 x4 : 0000000000000080 > x3 : 0000000000000000 x2 : 0000000000000000 > x1 : 0000000000000000 x0 : 00000000000003c8 > Call trace: > __lock_acquire+0x54/0x5ec > lock_acquire+0xe8/0x198 > _raw_spin_lock+0x70/0x88 > gs_read_complete+0x48/0xac > usb_gadget_giveback_request+0x48/0x80 > dwc3_gadget_giveback+0xcc/0xe8 > dwc3_remove_requests+0xa8/0x188 > __dwc3_gadget_ep_disable+0x98/0x110 > dwc3_gadget_ep_disable+0x50/0xbc > usb_ep_disable+0x44/0x94 > gserial_disconnect+0xc0/0x250 > acm_free_func+0x30/0x48 > usb_put_function+0x34/0x68 > config_usb_cfg_unlink+0xdc/0xf8 > configfs_unlink+0x144/0x264 > vfs_unlink+0x134/0x218 > do_unlinkat+0x13c/0x2a0 > __arm64_sys_unlinkat+0x48/0x60 > el0_svc_common.llvm.10277270529376503802+0xb8/0x1b4 > do_el0_svc+0x24/0x8c > el0_svc+0x10/0x1c > el0_sync_handler+0x68/0xac > el0_sync+0x18c/0x1c0 > > Signed-off-by: taehyun cho > --- > drivers/usb/gadget/function/u_serial.c | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c > index 6f68cbe..af08a18 100644 > --- a/drivers/usb/gadget/function/u_serial.c > +++ b/drivers/usb/gadget/function/u_serial.c > @@ -450,6 +450,15 @@ static void gs_read_complete(struct usb_ep *ep, struct usb_request *req) > { > struct gs_port *port = ep->driver_data; > > + /* > + * Port became NULL when 'dwc3_gadget_pullup' returns ETIMEDOUT. > + * Return here to avoid panic. > + */ > + if (!port) { > + pr_err("%s, failed to get port\n", __func__); > + return; > + } > + What prevents port from being null right after checking this? Where is the lock to prevent this? > /* Queue all received data until the tty layer is ready for it. */ > spin_lock(&port->port_lock); > list_add_tail(&req->list, &port->read_queue); > @@ -461,6 +470,15 @@ static void gs_write_complete(struct usb_ep *ep, struct usb_request *req) > { > struct gs_port *port = ep->driver_data; > > + /* > + * port became NULL when 'dwc3_gadget_pullup' returns ETIMEDOUT. > + * Return here to avoid panic. > + */ > + if (!port) { > + pr_err("%s, failed to get port\n", __func__); > + return; > + } Same here, where is the lock? And why report an error, what can a user do about it? thanks, greg k-h