From: Andrew Morton <akpm@linux-foundation.org>
To: Jan Engelhardt <jengelh@medozas.de>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] treewide: fix memory corruptions when TASK_COMM_LEN != 16
Date: Tue, 24 Jan 2012 13:54:43 -0800 [thread overview]
Message-ID: <20120124135443.2772d455.akpm@linux-foundation.org> (raw)
In-Reply-To: <1327183785-27023-1-git-send-email-jengelh@medozas.de>
On Sat, 21 Jan 2012 23:09:44 +0100
Jan Engelhardt <jengelh@medozas.de> wrote:
> I found that the kernel BUG()s out, already during boot, when bumping
> TASK_COMM_LEN to a value larger than 16
We can never increase TASK_COMM_LEN - it is part of the kernel ABI/API.
Doing so would destroy existing userspace which uses 16-byte buffers.
> (and I can imagine the same
> problem unfolding as well if it is set to something smaller).
hm, that's a surprise. Decreasing TASK_COMM_LEN is at least slightly
possible but it's hard to see why we should do so.
> Various places do insufficient length checks, simply assume certain
> sizes or hardcode things. Even though e.g. get_task_comm clearly
> documents that its buffer ought to be TASK_COMM_LEN long, I do believe
> that an extra size parameter, such as added in this patch, is a lot
> more robust than relying on callers getting the buffer size right.
>
> With this patch, I no longer experience crashes, but that is not to
> say that there are not any further places (e.g. in modules I never
> use) with flakey ->comm handling.
You do seem to have found a few warts around the task->comm handling.
But I don't believe that addressing them justifies adding new code
(adding another argument to get_task_comm).
If you're interested in working on this stuff I'd suggest that we
confine ourselves to cleaning things up (without adding code) rather
than permitting a different TASK_COMM_LEN. Things like replacing "16"
with TASK_COMM_LEN.
next prev parent reply other threads:[~2012-01-24 21:54 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-21 22:09 [PATCH 1/2] treewide: fix memory corruptions when TASK_COMM_LEN != 16 Jan Engelhardt
2012-01-21 22:09 ` [PATCH 2/2] treewide: avoid truncation of process name Jan Engelhardt
2012-01-24 21:54 ` Andrew Morton [this message]
2012-02-01 1:15 ` [PATCH 1/2] treewide: fix memory corruptions when TASK_COMM_LEN != 16 Jan Engelhardt
2012-02-01 1:23 ` Andrew Morton
2012-02-01 1:35 ` Jan Engelhardt
2012-02-01 1:49 ` Andrew Morton
2012-02-01 2:15 ` Jan Engelhardt
2012-02-01 3:01 ` Andrew Morton
2012-02-22 12:48 ` Jan Engelhardt
2012-02-22 20:58 ` Andrew Morton
2012-02-23 9:09 ` Jan Engelhardt
2012-02-23 9:57 ` Andrew Morton
2012-02-23 11:19 ` Jan Engelhardt
2012-02-23 17:30 ` Andrew Morton
2012-02-23 21:59 ` Jan Engelhardt
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