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>
110 lines
5.5 KiB
C
110 lines
5.5 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#pragma once
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#include "shared-forward.h"
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#define VERB_ANY (UINT_MAX)
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typedef enum VerbFlags {
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VERB_DEFAULT = 1 << 0, /* The verb to run if no verb is specified */
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VERB_ONLINE_ONLY = 1 << 1, /* Just do nothing when running in chroot or offline */
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VERB_GROUP_MARKER = 1 << 2, /* Fake verb entry to separate groups */
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} VerbFlags;
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/* Note: see the comment on struct Option in options.h for why _alignptr_ is required here. */
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typedef struct _alignptr_ {
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const char *verb;
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unsigned min_args, max_args;
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VerbFlags flags;
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int (* const dispatch)(int argc, char *argv[], uintptr_t data, void *userdata);
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uintptr_t data;
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const char *argspec;
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const char *help;
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} Verb;
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assert_cc(sizeof(Verb) % sizeof(void*) == 0);
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#define _VERB_DATA(d, v, a, amin, amax, f, dat, h) \
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_section_("SYSTEMD_VERBS") \
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_alignptr_ \
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_used_ \
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_retain_ \
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_no_reorder_ \
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_variable_no_sanitize_address_ \
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static const Verb CONCATENATE(verb_data_, __COUNTER__) = { \
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.verb = v, \
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.min_args = amin, \
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.max_args = amax, \
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.flags = f, \
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.dispatch = d, \
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.data = dat, \
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.argspec = a, \
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.help = h, \
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}
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/* Forward-define function d. scope specifies the scope, e.g. static. */
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#define VERB_SCOPE_FULL(scope, d, v, a, amin, amax, f, dat, h) \
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DISABLE_WARNING_REDUNDANT_DECLS \
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scope int d(int, char**, uintptr_t, void*); \
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REENABLE_WARNING \
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_VERB_DATA(d, v, a, amin, amax, f, dat, h)
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/* The same as VERB_SCOPE_FULL with scope hardwired to 'static'. */
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#define VERB_FULL(d, v, a, amin, amax, f, dat, h) \
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VERB_SCOPE_FULL(static, d, v, a, amin, amax, f, dat, h)
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/* The same as VERB_SCOPE_FULL/VERB_FULL, but without the data argument. */
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#define VERB_SCOPE(scope, d, v, a, amin, amax, f, h) \
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VERB_SCOPE_FULL(scope, d, v, a, amin, amax, f, /* dat= */ 0, h)
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#define VERB(d, v, a, amin, amax, f, h) \
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VERB_SCOPE(static, d, v, a, amin, amax, f, h)
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/* Simplified VERB_SCOPE/VERB for verbs that take no argument. */
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#define VERB_SCOPE_NOARG(scope, d, v, h) \
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VERB_SCOPE(scope, d, v, /* a= */ NULL, /* amin= */ VERB_ANY, /* amax= */ 1, /* f= */ 0, h)
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#define VERB_NOARG(d, v, h) \
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VERB_SCOPE_NOARG(static, d, v, h)
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#define VERB_DEFAULT_NOARG(d, v, h) \
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VERB_SCOPE(static, d, v, /* a= */ NULL, /* amin= */ VERB_ANY, /* amax= */ 1, /* f= */ VERB_DEFAULT, h)
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/* Magic entry in the table (which will not be returned) that designates the start of the group <gr>.
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* The macro works as a separator between groups and must be between other VERB* stanzas. */
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#define VERB_GROUP(gr) \
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_VERB_DATA(/* d= */ NULL, /* v= */ gr, /* a= */ NULL, /* amin= */ 0, /* amax= */ 0, \
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/* f= */ VERB_GROUP_MARKER, /* dat= */ 0, /* h= */ NULL)
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/* This is magically mapped to the beginning and end of the section */
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extern const Verb __start_SYSTEMD_VERBS[];
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extern const Verb __stop_SYSTEMD_VERBS[];
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bool running_in_chroot_or_offline(void);
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bool should_bypass(const char *env_prefix);
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const Verb* verbs_find_verb(const char *name, const Verb verbs[], const Verb verbs_end[]);
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int _dispatch_verb(char **args, const Verb verbs[], const Verb verbs_end[], void *userdata);
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#define dispatch_verb(args, userdata) \
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_dispatch_verb(args, __start_SYSTEMD_VERBS, __stop_SYSTEMD_VERBS, userdata)
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int _verbs_get_help_table(
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const Verb verbs[],
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const Verb verbs_end[],
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const char *group,
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Table **ret);
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#define verbs_get_help_table_group(group, ret) \
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_verbs_get_help_table(__start_SYSTEMD_VERBS, __stop_SYSTEMD_VERBS, group, ret)
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#define verbs_get_help_table(ret) \
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verbs_get_help_table_group(/* group= */ NULL, ret)
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#define _VERB_COMMON_HELP_IMPL(impl) \
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static int verb_help(int argc, char **argv, uintptr_t data, void *userdata) { \
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return impl(); \
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}
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#define VERB_COMMON_HELP(impl) \
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VERB(verb_help, "help", NULL, VERB_ANY, VERB_ANY, 0, "Show this help"); \
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_VERB_COMMON_HELP_IMPL(impl)
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#define VERB_COMMON_HELP_HIDDEN(impl) \
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VERB(verb_help, "help", NULL, VERB_ANY, VERB_ANY, 0, NULL); \
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_VERB_COMMON_HELP_IMPL(impl)
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