From mboxrd@z Thu Jan 1 00:00:00 1970 From: YOSHIFUJI Hideaki Subject: Re: [PATCH] isdnloop: NUL-terminate strings from userspace Date: Tue, 01 Apr 2014 20:23:44 +0900 Message-ID: <533AA1C0.8030609@yoshifuji.org> References: <1396346898-8950-1-git-send-email-vegard.nossum@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, Dan Carpenter , "David S. Miller" , stable@vger.kernel.org, YOSHIFUJI Hideaki To: Vegard Nossum , netdev@vger.kernel.org Return-path: In-Reply-To: <1396346898-8950-1-git-send-email-vegard.nossum@oracle.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Vegard Nossum wrote: > Both the in-kernel and BSD strlcpy() require that the source string is > NUL terminated. We could use strncpy() + explicitly terminate the result, > but this relies on src and dest having the same size, so the safest thing > to do seems to explicitly terminate the source string before doing the > strlcpy(). : > diff --git a/drivers/isdn/isdnloop/isdnloop.c b/drivers/isdn/isdnloop/isdnloop.c > index 02125e6..50cd348 100644 > --- a/drivers/isdn/isdnloop/isdnloop.c > +++ b/drivers/isdn/isdnloop/isdnloop.c > @@ -1070,6 +1070,14 @@ isdnloop_start(isdnloop_card *card, isdnloop_sdef *sdefp) > return -EBUSY; > if (copy_from_user((char *) &sdef, (char *) sdefp, sizeof(sdef))) > return -EFAULT; > + > + /* > + * Null terminate strings from userspace so we don't have to worry > + * about this later on. > + */ > + for (i = 0; i < 3; i++) > + sdef.num[i][sizeof(sdef.num[0]) - 1] = '\0'; > + Why don't we return -EINVAL if it is not correctly terminated by NUL? --yoshfuji