linux-kernel - Re: [PATCH] clean up scary strncpy(dst, src, strlen(src)) uses

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 5 Jun 2013 17:11:23 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	linux-acpi@...r.kernel.org, linux-s390@...r.kernel.org,
	devel@...verdev.osuosl.org,
	user-mode-linux-devel@...ts.sourceforge.net
Subject: Re: [PATCH] clean up scary strncpy(dst, src, strlen(src)) uses

On Wed, Jun 5, 2013 at 4:48 PM, Andrew Morton <akpm@...ux-foundation.org> wrote:
> On Fri, 31 May 2013 09:18:07 -0700 Kees Cook <keescook@...omium.org> 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 <sys/socket.h>
>>  #include <sys/wait.h>
>>  #include <signal.h>
>> +#include <bsd/string.h>
>>
>>  #include <linux/genetlink.h>
>>  #include <linux/taskstats.h>
>> @@ -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@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/