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

[Kees Cook]

On Wed, Jun 5, 2013 at 4:48 PM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Fri, 31 May 2013 09:18:07 -0700 Kees Cook <keescook@xxxxxxxxxxxx> 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
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