From patchwork Tue Sep 17 16:47:23 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alan Stern X-Patchwork-Id: 11149209 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 34EDB13BD for ; Tue, 17 Sep 2019 16:47:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 149EE2171F for ; Tue, 17 Sep 2019 16:47:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727038AbfIQQrY (ORCPT ); Tue, 17 Sep 2019 12:47:24 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:38888 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1725847AbfIQQrY (ORCPT ); Tue, 17 Sep 2019 12:47:24 -0400 Received: (qmail 5432 invoked by uid 2102); 17 Sep 2019 12:47:23 -0400 Received: from localhost (sendmail-bs@127.0.0.1) by localhost with SMTP; 17 Sep 2019 12:47:23 -0400 Date: Tue, 17 Sep 2019 12:47:23 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Greg KH cc: Tomoki Sekiyama , , , USB list , Subject: [PATCH] USB: yurex: Don't retry on unexpected errors In-Reply-To: <0000000000001603470592b13bfc@google.com> Message-ID: MIME-Version: 1.0 Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org According to Greg KH, it has been generally agreed that when a USB driver encounters an unknown error (or one it can't handle directly), it should just give up instead of going into a potentially infinite retry loop. The three codes -EPROTO, -EILSEQ, and -ETIME fall into this category. They can be caused by bus errors such as packet loss or corruption, attempting to communicate with a disconnected device, or by malicious firmware. Nowadays the extent of packet loss or corruption is negligible, so it should be safe for a driver to give up whenever one of these errors occurs. Although the yurex driver handles -EILSEQ errors in this way, it doesn't do the same for -EPROTO (as discovered by the syzbot fuzzer) or other unrecognized errors. This patch adjusts the driver so that it doesn't log an error message for -EPROTO or -ETIME, and it doesn't retry after any errors. Reported-and-tested-by: syzbot+b24d736f18a1541ad550@syzkaller.appspotmail.com Signed-off-by: Alan Stern CC: Tomoki Sekiyama CC: --- [as1918] drivers/usb/misc/yurex.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) Index: usb-devel/drivers/usb/misc/yurex.c =================================================================== --- usb-devel.orig/drivers/usb/misc/yurex.c +++ usb-devel/drivers/usb/misc/yurex.c @@ -132,6 +132,7 @@ static void yurex_interrupt(struct urb * switch (status) { case 0: /*success*/ break; + /* The device is terminated or messed up, give up */ case -EOVERFLOW: dev_err(&dev->interface->dev, "%s - overflow with length %d, actual length is %d\n", @@ -140,12 +141,13 @@ static void yurex_interrupt(struct urb * case -ENOENT: case -ESHUTDOWN: case -EILSEQ: - /* The device is terminated, clean up */ + case -EPROTO: + case -ETIME: return; default: dev_err(&dev->interface->dev, "%s - unknown status received: %d\n", __func__, status); - goto exit; + return; } /* handle received message */ @@ -177,7 +179,6 @@ static void yurex_interrupt(struct urb * break; } -exit: retval = usb_submit_urb(dev->urb, GFP_ATOMIC); if (retval) { dev_err(&dev->interface->dev, "%s - usb_submit_urb failed: %d\n",