Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755955AbbDUT0A (ORCPT ); Tue, 21 Apr 2015 15:26:00 -0400 Received: from mout.gmx.net ([212.227.17.20]:60849 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755545AbbDUTZ6 (ORCPT ); Tue, 21 Apr 2015 15:25:58 -0400 Message-ID: <5536A435.1030808@gmx.de> Date: Tue, 21 Apr 2015 21:25:41 +0200 From: Heinrich Schuchardt User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.6.0 MIME-Version: 1.0 To: Peter Chen CC: Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] drivers/usb/chipidea/debuc.c: avoid out of bound read References: <1429250653-1626-1-git-send-email-xypron.glpk@gmx.de> <20150421013254.GA25710@shlinux2> In-Reply-To: <20150421013254.GA25710@shlinux2> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Provags-ID: V03:K0:817moenn/RtJe7e+NchzcTR/qkIdF1PqJ8lGF4jpMNrxJC2fNLX 2XQxw0luykHwT5IrHBuxqpCy2ZE924UjIWD7zRfHuibgRvjKQ9JXRartSdChamoX7bC6T2w 96CegD8/Q8JG3ARvdKNZAx3R9EF4b0n95Tg/i8Xs18wGnhfxTVuXzhzv8y5ShrYd5W7NIz7 +IFuDOgXCNMT8KYhW+Svw== X-UI-Out-Filterresults: notjunk:1; Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1654 Lines: 59 Hello Peter, thanks for reviewing. On 21.04.2015 03:32, Peter Chen wrote: > On Fri, Apr 17, 2015 at 08:04:13AM +0200, Heinrich Schuchardt wrote: >> A string written by the user may not be zero terminated. >> >> sscanf may read memory beyond the buffer if no zero byte >> is found. >> >> Signed-off-by: Heinrich Schuchardt >> --- >> drivers/usb/chipidea/debug.c | 6 +++++- >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/usb/chipidea/debug.c b/drivers/usb/chipidea/debug.c >> index dfb05ed..ef08af3 100644 >> --- a/drivers/usb/chipidea/debug.c >> +++ b/drivers/usb/chipidea/debug.c >> @@ -88,9 +88,13 @@ static ssize_t ci_port_test_write(struct file *file, const char __user *ubuf, >> char buf[32]; >> int ret; >> >> - if (copy_from_user(buf, ubuf, min_t(size_t, sizeof(buf) - 1, count))) >> + count = min_t(size_t, sizeof(buf) - 1, count); >> + if (copy_from_user(buf, ubuf, count)) >> return -EFAULT; > > Any reasons to change above? Otherwise we would have two lines with the term min_t(size_t, sizeof(buf) - 1, count). This would make the code harder to read. >> >> + /* sscanf requires a zero terminated string */ >> + buf[count] = 0; >> + > > I prefer using '\0' If you confirm the rest of the patch is ok, I will send an updated patch. Best regards Heinrich > >> if (sscanf(buf, "%u", &mode) != 1) >> return -EINVAL; >> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/