Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754906Ab3FFAL0 (ORCPT ); Wed, 5 Jun 2013 20:11:26 -0400 Received: from mail-ie0-f175.google.com ([209.85.223.175]:59177 "EHLO mail-ie0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754365Ab3FFALY (ORCPT ); Wed, 5 Jun 2013 20:11:24 -0400 MIME-Version: 1.0 In-Reply-To: <20130605164804.8071867d28c1f20cad8d7d2a@linux-foundation.org> References: <20130531161807.GA9536@www.outflux.net> <20130605164804.8071867d28c1f20cad8d7d2a@linux-foundation.org> Date: Wed, 5 Jun 2013 17:11:23 -0700 X-Google-Sender-Auth: cgINe0tHOZvWCjQMXA0CffcIkoA Message-ID: Subject: Re: [PATCH] clean up scary strncpy(dst, src, strlen(src)) uses From: Kees Cook To: Andrew Morton Cc: LKML , "linux-doc@vger.kernel.org" , linux-acpi@vger.kernel.org, linux-s390@vger.kernel.org, devel@driverdev.osuosl.org, user-mode-linux-devel@lists.sourceforge.net Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1922 Lines: 50 On Wed, Jun 5, 2013 at 4:48 PM, Andrew Morton wrote: > On Fri, 31 May 2013 09:18:07 -0700 Kees Cook wrote: > >> Fix various weird constructions of strncpy(dst, src, strlen(src)). Length >> limits should be about the space available in the destination, not >> repurposed as a method to either always include or always exclude >> a trailing NULL byte. Either the NULL should always be copied >> (using strlcpy), or it should not be copied (using something like >> memcpy). Readable code should not depend on the weird behavior of strncpy >> when it hits the length limit. Better to avoid the anti-pattern entirely. >> >> ... >> >> --- a/Documentation/accounting/getdelays.c >> +++ b/Documentation/accounting/getdelays.c >> @@ -23,6 +23,7 @@ >> #include >> #include >> #include >> +#include >> >> #include >> #include >> @@ -299,7 +300,7 @@ int main(int argc, char *argv[]) >> break; >> case 'C': >> containerset = 1; >> - strncpy(containerpath, optarg, strlen(optarg) + 1); >> + strlcpy(containerpath, optarg, sizeof(containerpath)); >> break; >> case 'w': >> logfile = strdup(optarg); > > Documentation/accounting/getdelays.c:26:24: fatal error: bsd/string.h: No such file or directory > > I'll revert this part. Ah, hrm. Well, in that case, it should use strdup, as logfile does already. Do you want me to send a patch for that? -Kees -- Kees Cook Chrome OS Security -- 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/