From: Al Viro <viro@ZenIV.linux.org.uk>
To: Christian Brauner <christian@brauner.io>
Cc: keescook@chromium.org, linux-kernel@vger.kernel.org,
ebiederm@xmission.com, mcgrof@kernel.org,
akpm@linux-foundation.org, joe.lawrence@redhat.com,
longman@redhat.com, linux@dominikbrodowski.net,
adobriyan@gmail.com, linux-api@vger.kernel.org,
Andrea Arcangeli <aarcange@redhat.com>,
Miklos Szeredi <miklos@szeredi.hu>,
Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH v3 2/2] sysctl: handle overflow for file-max
Date: Wed, 17 Oct 2018 01:35:48 +0100 [thread overview]
Message-ID: <20181017003548.GA32577@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20181016223322.16844-3-christian@brauner.io>
On Wed, Oct 17, 2018 at 12:33:22AM +0200, Christian Brauner wrote:
> Currently, when writing
>
> echo 18446744073709551616 > /proc/sys/fs/file-max
>
> /proc/sys/fs/file-max will overflow and be set to 0. That quickly
> crashes the system.
> This commit sets the max and min value for file-max and returns -EINVAL
> when a long int is exceeded. Any higher value cannot currently be used as
> the percpu counters are long ints and not unsigned integers. This behavior
> also aligns with other tuneables that return -EINVAL when their range is
> exceeded. See e.g. [1], [2] and others.
Mostly sane, but... get_max_files() users are bloody odd. The one in
file-max limit reporting looks like a half-arsed attempt in "[PATCH] fix
file counting". The one in af_unix.c, though... I don't remember how
that check had come to be - IIRC that was a strange fallout of a thread
with me, Andrea and ANK involved, circa 1999, but I don't remember details;
Andrea, any memories? It might be worth reconsidering... The change in
question is in 2.2.4pre6; what do we use unix_nr_socks for? We try to
limit the number of PF_UNIX socks by 2 * max_files, but max_files can be
huge *and* non-constant (i.e. it can decrease). What's more, unix_tot_inflight
is unsigned int and max_files might exceed 2^31 just fine since "fs: allow
for more than 2^31 files" back in 2010... Something's fishy there...
next prev parent reply other threads:[~2018-10-17 0:35 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-16 22:33 [PATCH v3 0/2] sysctl: handle overflow for file-max Christian Brauner
2018-10-16 22:33 ` [PATCH v3 1/2] sysctl: handle overflow in proc_get_long Christian Brauner
2018-10-16 23:45 ` Eric W. Biederman
2018-10-17 0:24 ` Christian Brauner
2018-10-17 2:19 ` Kees Cook
2018-10-16 22:33 ` [PATCH v3 2/2] sysctl: handle overflow for file-max Christian Brauner
2018-10-17 0:35 ` Al Viro [this message]
2018-10-17 9:57 ` Christian Brauner
2018-10-18 21:58 ` Andrea Arcangeli
2018-10-16 22:36 ` [PATCH v3 0/2] " Kees Cook
2018-10-29 14:58 ` Christian Brauner
2018-10-29 21:44 ` Kees Cook
2018-12-09 16:40 ` Christian Brauner
2018-12-10 17:51 ` Kees Cook
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20181017003548.GA32577@ZenIV.linux.org.uk \
--to=viro@zeniv.linux.org.uk \
--cc=aarcange@redhat.com \
--cc=adobriyan@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=christian@brauner.io \
--cc=ebiederm@xmission.com \
--cc=eric.dumazet@gmail.com \
--cc=joe.lawrence@redhat.com \
--cc=keescook@chromium.org \
--cc=linux-api@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@dominikbrodowski.net \
--cc=longman@redhat.com \
--cc=mcgrof@kernel.org \
--cc=miklos@szeredi.hu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).