From: Jakub Jankowski <shasta@toxcorp.com>
To: Alexey Izbyshev <izbyshev@ispras.ru>,
Alexey Dobriyan <adobriyan@gmail.com>,
Oleg Nesterov <oleg@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
security@kernel.org
Subject: Re: [PATCH] proc: Fix uninitialized byte read in get_mm_cmdline()
Date: Fri, 12 Jul 2019 23:17:03 +0200 (CEST) [thread overview]
Message-ID: <alpine.LNX.2.21.1907122312190.8869@kich.toxcorp.com> (raw)
In-Reply-To: <3de2d71b-37be-6238-7fd8-0a40c9b94a98@ispras.ru>
On 2019-07-12, Alexey Izbyshev wrote:
> On 7/12/19 8:46 PM, Alexey Dobriyan wrote:
>> The proper fix to all /proc/*/cmdline problems is to revert
>>
>> f5b65348fd77839b50e79bc0a5e536832ea52d8d
>> proc: fix missing final NUL in get_mm_cmdline() rewrite
>>
>> 5ab8271899658042fabc5ae7e6a99066a210bc0e
>> fs/proc: simplify and clarify get_mm_cmdline() function
>>
> Should this be interpreted as an actual suggestion to revert the patches,
> fix the conflicts, test and submit them, or is this more like thinking out
> loud? In the former case, will it be OK for long term branches?
>
> get_mm_cmdline() does seem easier to read for me before 5ab8271899658042.
> But it also has different semantics in corner cases, for example:
>
> - If there is no NUL at arg_end-1, it reads only the first string in
> the combined arg/env block, and doesn't terminate it with NUL.
>
> - If there is any problem with access_remote_vm() or copy_to_user(),
> it returns -EFAULT even if some data were copied to userspace.
>
> On the other hand, 5ab8271899658042 was merged not too long ago (about a year),
> so it's possible that the current semantics isn't heavily relied upon.
I posted this (corner?) case ~3 months ago, unfortunately it wasn't picked
up by anyone: https://lkml.org/lkml/2019/4/5/825
You can treat it as another datapoint in this discussion.
Regards,
Jakub
--
Jakub Jankowski|shasta@toxcorp.com|https://toxcorp.com/
next prev parent reply other threads:[~2019-07-12 21:26 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-12 16:09 [PATCH] proc: Fix uninitialized byte read in get_mm_cmdline() Alexey Izbyshev
2019-07-12 16:36 ` Oleg Nesterov
2019-07-12 17:46 ` Alexey Dobriyan
2019-07-12 18:43 ` Alexey Izbyshev
2019-07-12 21:17 ` Jakub Jankowski [this message]
2019-07-12 22:29 ` Alexey Izbyshev
2019-07-13 7:26 ` Alexey Dobriyan
2019-07-13 14:09 ` Alexey Izbyshev
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