linux-kernel - Re: [PATCH 1/3] mm/vmalloc: fix size check for remap_vmalloc_range

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:   Fri, 04 Jan 2019 11:21:39 +0100
From:   Roman Penyaev <rpenyaev@...e.de>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Joe Perches <joe@...ches.com>,
        "Luis R. Rodriguez" <mcgrof@...nel.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH 1/3] mm/vmalloc: fix size check for
 remap_vmalloc_range_partial()

On 2019-01-04 10:38, Michal Hocko wrote:

[...]

>> >
>> > OK, my response was more confusing than I intended. I meant to say. Is
>> > there any in kernel code that would allow the bug have had in mind?
>> > In other words can userspace trick any existing code?
>> 
>> In theory any existing caller of remap_vmalloc_range() which does
>> not have an explicit size check should trigger an oops, e.g. this is
>> a good candidate:
>> 
>> *** drivers/media/usb/stkwebcam/stk-webcam.c:
>> v4l_stk_mmap[789]              ret = remap_vmalloc_range(vma, 
>> sbuf->buffer,
>> 0);
> 
> Hmm, sbuf->buffer is allocated in stk_setup_siobuf to have
> buf->v4lbuf.length. mmap callback maps this buffer to the vma size and
> that is indeed not enforced to be <= length AFAICS. So you are right!
> 
> Can we have an example in the changelog please?

You mean to resend this particular patch with the list of possible
candidates for oops in a comment message?  Sure thing.

--
Roman