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

[Russell Coker]

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
ii  liblzma5                                        5.6.2-2
pn  libtss2-rc0t64                                  <none>
ii  libtss2-tcti-device0t64 [libtss2-tcti-device0]  4.1.3-1
ii  polkitd                                         125-2
pn  systemd-boot                                    <none>
ii  systemd-container                               256.5-1
pn  systemd-homed                                   <none>
pn  systemd-repart                                  <none>
ii  systemd-resolved                                256.5-1
pn  systemd-userdbd                                 <none>

Versions of packages systemd is related to:
ii  dbus-user-session  1.14.10-4+b1
pn  dracut             <none>
ii  initramfs-tools    0.145
ii  libnss-systemd     256.5-1
ii  libpam-systemd     256.5-1
ii  udev               256.5-1

-- Configuration Files:
/etc/systemd/journald.conf [Errno 13] Permission denied: '/etc/systemd/journald.conf'

-- debconf-show failed