linux-kernel - Re: [PATCH] Block: Fix block/elevator.c elevator

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] [day] [month] [year] [list]

Date:	Fri, 2 Apr 2010 15:14:42 +0800
From:	Xiaotian Feng <xtfeng@...il.com>
To:	wzt.wzt@...il.com
Cc:	linux-kernel@...r.kernel.org, axboe@...nel.dk
Subject: Re: [PATCH] Block: Fix block/elevator.c elevator_get() off-by-one 
	error

On Tue, Mar 30, 2010 at 5:21 PM,  <wzt.wzt@...il.com> wrote:
> elevator_get() not check the name length, if the name length > sizeof(elv),
> elv will miss the '\0'. And elv buffer will be replace "-iosched" as something
> like aaaaaaaaa, then call request_module() can load an not trust module.
>
> Signed-off-by: Zhitong Wang <zhitong.wangzt@...baba-inc.com>
>
> ---
>  block/elevator.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/block/elevator.c b/block/elevator.c
> index df75676..76e3702 100644
> --- a/block/elevator.c
> +++ b/block/elevator.c
> @@ -154,7 +154,7 @@ static struct elevator_type *elevator_get(const char *name)
>
>                spin_unlock(&elv_list_lock);
>
> -               sprintf(elv, "%s-iosched", name);
> +               snprintf(elv, sizeof(elv), "%s-iosched", name);
>

elv is defined as char elv[ELV_NAME_MAX + strlen("-iosched")];
so if name length > sizeof(elv), the name length must already bigger
than ELV_NAME_MAX

elevator_get is used in elevator_init, so if elevator_init is passing
a super long name, why not just return -EINVAL?
In this patch, if we pass a super long name, we're still trying to cut
it and request_module an invalid name, right?
Although '\0' is kept, but name is still invalid, right?


>                request_module("%s", elv);
>                spin_lock(&elv_list_lock);
> --
> 1.6.5.3
>
> --
> 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/
>
--
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/