Without the size limits, oss-fuzz creates huge samples that time out. Usually
this is because some of our code has bad algorithmic complexity. For data like
configuration samples we don't need to care about this: non-rogue configs are
rarely more than a few items, and a bit of a slowdown with a few hundred items
is acceptable. This wouldn't be OK for processing of untrusted data though.
We need to set the limit in two ways: through .options and in the code. The
first because it nicely allows libFuzzer to avoid wasting time, and the second
because fuzzers like hongfuzz and afl don't support .options.
While at it, let's fix an off-by-one (65535 is the largest offset for a
power-of-two size, but we're checking the size here).
Co-authored-by: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
With an intentional mistake:
../src/login/logind-dbus.c: In function ‘bus_manager_log_shutdown’:
../src/login/logind-dbus.c:1542:39: error: format ‘%s’ expects a matching ‘char *’ argument [-Werror=format=]
1542 | LOG_MESSAGE("%s %s", message),
| ^~~~~~~
Also break some long lines for more uniform formatting. No functional change.
I went over all log_struct, log_struct_errno, log_unit_struct,
log_unit_struct_errno calls, and they seem fine.
This is trivially exploitable (in the sense of causing a crash from SEGV) e.g.
by 'shutdown now "Message %s %s %n"'. The message is settable through polkit,
but is limited to auth_admin:
<action id="org.freedesktop.login1.set-wall-message">
<description gettext-domain="systemd">Set a wall message</description>
<message gettext-domain="systemd">Authentication is required to set a wall message</message>
<defaults>
<allow_any>auth_admin_keep</allow_any>
<allow_inactive>auth_admin_keep</allow_inactive>
<allow_active>auth_admin_keep</allow_active>
</defaults>
</action>
Bug introduced in 9ef15026c0
('logind/systemctl: introduce SetWallMessage and --message', 2015-09-15).
This normally wouldn't happen, but if some of those places were called
with lhs and rhs being the same object, we could unref the last ref first,
and then try to take the ref again. It's easier to be safe, and with the
helper we save some lines too.
We canonicalize repeats that cover the whole range: "0:0:0/1" → "0:0:*". But
we'd also do "0:0:0/1,0" → "0:0:*,0", which we then refuse to parse. Thus,
first go throug the whole chain, and print a '*' and nothing else if any of the
components covers the whole range.
0..3 is not the same as 0..infinity, we need to check both ends of the range.
This logic was added in 3215e35c40, and back then
the field was called .value. .stop was added later and apparently wasn't taken
into account here.
Coverage data shows that we didn't test calendar_spec_next_usec() and
associated functions at all.
The input samples so far were only used until the first NUL. We take advantage
of that by using the part until the second NUL as the starting timestamp,
retaining backwards compatibility for how the first part is used.
calendar_spec_from_string() already calls calendar_spec_normalize(), so
there is no point in calling it from the fuzzer. Once that's removed, there's
just one internal caller and it can be made static.
