linux-kernel - Re: [PATCH v2 21/29] nios2: Futex operations

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:	Thu, 17 Jul 2014 18:55:49 +0800
From:	Ley Foon Tan <lftan@...era.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Linux-Arch <linux-arch@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	Chung-Lin Tang <cltang@...esourcery.com>
Subject: Re: [PATCH v2 21/29] nios2: Futex operations

On Tue, Jul 15, 2014 at 6:03 PM, Thomas Gleixner <tglx@...utronix.de> wrote:
> On Tue, 15 Jul 2014, Ley Foon Tan wrote:
>  +static inline int atomic_futex_op_xchg_set(int oparg, u32 __user *uaddr,
>> +                                        int *oldval)
>> +{
>> +     unsigned long flags;
>> +     int ret;
>> +
>> +     local_irq_save(flags);
>> +
>> +     ret = get_user(*oldval, uaddr);
>> +     if (!ret)
>> +             ret = put_user(oparg, uaddr);
>
> This is wrong as it gets. get_user() might fault and sleep.
>
> You need a proper implementation, which handles fault exceptions.
I have checked that we use nios2 specific get_user() in [1]. This
function will not sleep and it handles fault exception.
I think this should be fine.

[1] http://rocketboards.org/gitweb/?p=linux-socfpga-next.git;a=blob;f=arch/nios2/include/asm/uaccess.h;h=3e36f536afaba24c308a8416a66b8a2573e042a5;hb=refs/heads/nios2-upstream

Regards
Ley Foon
--
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/