linux-kernel - Re: BUG: KASAN: global-out-of-bounds in strscpy+0x807/0x970

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-next>] [day] [month] [year] [list]

Message-ID: <411eec08-711a-d133-05bf-0e6c7d4101d3@canonical.com>
Date:   Wed, 11 Oct 2017 00:37:43 -0400
From:   Tyler Hicks <tyhicks@...onical.com>
To:     Jakub Kicinski <kubakici@...pl>, Kees Cook <keescook@...omium.org>
Cc:     Simon Brewer <sbrunau@...il.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: BUG: KASAN: global-out-of-bounds in strscpy+0x807/0x970

On 10/10/2017 10:32 PM, Simon Brewer wrote:
> Hint start looking at this thread. https://lkml.org/lkml/2017/7/18/874
> 
> Summary: strscpy and KASAN are currently incompatible.  strscpy does a
> 64 bit speculative fetch on a char pointer (for efficiency reasons). 
> KASAN spots this and flags an error.

Thanks, Simon. I had already reviewed the loop in
seccomp_names_from_actions_logged() and couldn't spot an issue so my
next step was to take a look at strscpy() itself. Your reply was well
timed. :)

@Kees, this is a false positive. I picked strscpy() because of its sane
return codes for easy error handling but its word-at-a-time complexity
is overkill for this sysctl. Are you alright with this KASAN false
positive or would you like me to change over to strlcpy()?

Tyler

> 
> On 11 October 2017 at 12:46, Jakub Kicinski <kubakici@...pl
> <mailto:kubakici@...pl>> wrote:
> 
>     On Tue, 10 Oct 2017 21:44:01 -0400, Tyler Hicks wrote:
>     > On 10/10/2017 09:28 PM, Jakub Kicinski wrote:
>     > > I'm hitting this on sysctl -a with net-next (4.14-rc4).
>     >
>     > Hey Jakub - thanks for the bug report!
>     >
>     > >
>     > > I saw that seccomp_actions_logged_handler was introduced
>     > > not-so-long-ago by Tyler, is there a fix for this?
>     >
>     > No, this is the first I've heard of it. I'll have a look.
> 
>     Thanks! :)
> 
> 




Download attachment "signature.asc" of type "application/pgp-signature" (802 bytes)