linux-kernel - Re: A simple question of sys

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 for Android: free password hash cracker in your pocket

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

Date:	Mon, 20 Sep 2010 16:34:26 +0800
From:	Rofail Qu <rofail@...il.com>
To:	Randy Dunlap <rdunlap@...otime.net>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: A simple question of sys_

2010/9/18 Randy Dunlap <rdunlap@...otime.net>:
> On Fri, 17 Sep 2010 14:58:30 +0800 Rofail Qu wrote:
>
>> How to use macro IS_ERR() ?
>>
>> It defines as,
>> ...
>> #define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)
>> static inline long __must_check IS_ERR(const void *ptr)
>> {
>>       return IS_ERR_VALUE((unsigned long)ptr);
>> }
>> ...
>> so when pass x as a pointer and x>=-MAX_ERRNO (including NULL or any
>> valid address),
>> IS_ERR() will return true!
>
> Since your conclusion is false, some part of your premise must have a problem.
> Can you find it?
Got it.
thanks any way.

>
>
>> IS_ERR(x) seems to use on judge if "x" is a valid error number, right?
>
> Yes, that's what it is for.
So in kernel, a bad pointer must have saved an valid error number, right?

>
>> So in sys_execve(),
>> ...
>>         long error;
>>       char* filename;
>>
>>       filename = getname(name);
>>       error = PTR_ERR(filename);
>>       if (IS_ERR(filename))     // <== should be IS_ERR((void *)error) or other?
>>               return error;
>>       error = do_execve(filename, argv, envp, regs);
>> ...
>>
>> Where i am wrong?
>
>
> ---
> ~Randy
> *** Remember to use Documentation/SubmitChecklist when testing your code ***
>
--
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/