Luca Boccassi
a7ecad77cb
On some architectures like m68k, alignof(void*) is 2, not sizeof(void*)
(which is 4). So the natural alignment of struct Option is 2 and
sizeof(Option) == 26.
However, each variable placed in the SYSTEMD_OPTIONS ELF section via
_OPTION() carries _alignptr_ (= __attribute__((aligned(sizeof(void*))))),
which forces each entry to start at a 4-byte boundary. The linker
therefore inserts 2 bytes of padding between adjacent entries, producing
an actual stride of 28 in the section.
option_parse() iterates over the section with pointer arithmetic
("opt++"), which advances by sizeof(Option) == 26 and lands inside the
padding. The fields read back as zero, and since commit cf88903637
("tree-wide: get rid of most uses of ALIGN_PTR") added the ordering
assertion below, the resulting "0 < 0" trips it when running --help:
Assertion 'opt->id < (opt + 1)->id' failed at src/shared/options.c:116, function option_parse(). Aborting.
#0 0xc0a7b248 in ?? () from /usr/lib/m68k-linux-gnu/libc.so.6
#1 0xc0a7b2ce in pthread_kill () from /usr/lib/m68k-linux-gnu/libc.so.6
#2 0xc0a2edc6 in raise () from /usr/lib/m68k-linux-gnu/libc.so.6
#3 0xc0a1c128 in abort () from /usr/lib/m68k-linux-gnu/libc.so.6
#4 0xc05c6f78 in option_parse (options=0x0, options_end=0x0, state=0xc09ca968) at ../src/shared/options.c:116
Fix this by applying _alignptr_ to the struct definition itself, so that
sizeof(Option) is padded up to a multiple of sizeof(void*) and matches
the actual on-disk stride. Add an assert_cc() so any future regression
is caught at compile time.
The same latent bug applies to Verb and TestFunc, which use the same
section-placement pattern. Their natural sizeof was already a multiple
of sizeof(void*) so no crash was observed, but apply the same fix
defensively.
Follow-up for cf88903637
Co-developed-by: Claude Opus 4.7 <noreply@anthropic.com>
System and Service Manager
Details
Most documentation is available on systemd's web site.
Assorted, older, general information about systemd can be found in the systemd Wiki.
Information about build requirements is provided in the README file.
Consult our NEWS file for information about what's new in the most recent systemd versions.
Please see the Code Map for information about this repository's layout and content.
Please see the Hacking guide for information on how to hack on systemd and test your modifications.
Please see our Contribution Guidelines for more information about filing GitHub Issues and posting GitHub Pull Requests.
When preparing patches for systemd, please follow our Coding Style Guidelines.
If you are looking for support, please contact our mailing list, join our IRC channel #systemd on libera.chat or Matrix channel
Stable branches with backported patches are available in the stable repo.
We have a security bug bounty program sponsored by the Sovereign Tech Fund hosted on YesWeHack
Repositories with distribution packages built from git main are available on OBS, and also repositories with packages built from the latest stable release