Bug#1079670: systemd: should restrict size of /dev tmpfs

[Patrice Duroux]

Hi,

Interesting to look also at:
https://codesearch.debian.net/search?q=%2Fdev%2Fnul%5B%5El%5D&literal=0

This reminds me of my hunt for mistakes like 2&>1 in place of 2>&1:
https://lists.debian.org/debian-qa/2023/02/msg00052.html
both in some packaging scripts and in upstream sources.
Many of them have since been resolved.

Regards,
Patrice

On Mon, 26 Aug 2024 15:22:47 +1000 Russell Coker <russell at coker.com.au> wrote:
> Package: systemd
> Version: 256.5-1
> Severity: minor
> 
> https://current.workingdirectory.net/posts/2024/who-ate-my-ram/
> 
> The above blog post from Planet Debian shows an issue that isn't that uncommon
> of running out of RAM due to writing to the wrong name under /dev (eg writing
> to /dev/nul).
> 
> While the script in question shouldn't do that it would be good to have the
> result of doing so not involve making a server unusable.
> 
> The command "mount -o remount,size=10m /dev" reduces the size and potential
> wasted RAM to 10M which prevents this sort of thing from becoming a serious
> problem and has no downsides that I can imagine.  10M should be more than
> enough for the systems with the largest numbers of devices.
> 
> I'm filing this bug report against systemd because it's related to boot
> scripts and I can't think of a better target.
> 
> -- Package-specific info:
> 
> -- System Information:
> Debian Release: trixie/sid
> Architecture: amd64 (x86_64)
> 
> Kernel: Linux 6.10.6-amd64 (SMP w/4 CPU threads; PREEMPT)
> Locale: LANG=en_AU.UTF-8, LC_CTYPE=en_AU.UTF-8 (charmap=UTF-8),
LANGUAGE=en_AU:en
> Shell: /bin/sh linked to /usr/bin/dash
> Init: unable to detect
> 
> Versions of packages systemd depends on:
> ii  libacl1            2.3.2-2
> ii  libapparmor1       3.1.7-1+b1
> ii  libaudit1          1:4.0.1-1
> ii  libblkid1          2.40.2-7
> ii  libc6              2.39-7
> ii  libcap2            1:2.66-5
> ii  libmount1          2.40.2-7
> ii  libpam0g           1.5.3-7
> ii  libseccomp2        2.5.5-1+b1
> ii  libselinux1        3.7-1+b1
> ii  libssl3t64         3.3.1-7
> ii  libsystemd-shared  256.5-1
> ii  libsystemd0        256.5-1
> ii  mount              2.40.2-7
> 
> Versions of packages systemd recommends:
> ii  dbus [default-dbus-system-bus]   1.14.10-4+b1
> ii  libzstd1                         1.5.6+dfsg-1
> pn  linux-sysctl-defaults            <none>
> pn  systemd-cryptsetup               <none>
> ii  systemd-timesyncd [time-daemon]  256.5-1
> 
> Versions of packages systemd suggests:
> ii  libcryptsetup12                                 2:2.7.4-1
> ii  libgcrypt20                                     1.11.0-6
> ii  libidn2-0                                       2.3.7-2
> ii  liblz4-1                                        1.9.4-3