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systemd: fix NULL dereference when disabling a nonexistent instance

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Assertion 'p' failed at src/shared/path-util.c:51, function path_get_file_name(). Aborting.

The unit file could not be found, and i->path would not be set.
In 02b9e969 a code path was added which attempts to remove symlinks
to a nonexistent (removed) unit file. This worked OK in case of
non-instance services, but broke in the case of instance services.

Behaviour wrt. to instance units is changed in the way that 02b9e969
changed it for non-instance units: it is now possible to remove
instance symlinks to a template unit that has been removed.

This patch isn't a full fix, because the behaviour wrt. to enabling
and disabling instance units is still broken: e.g it is possible to
start autovt@tty5.service, but it is not possible to enable it,
because autovt@.service is a symlink, and on the other hand, disabling
getty@tty5.service removes all symlinks to getty@.service, which is
wrong too. But segfaults make bad pr, so let's add at least this
partial fix for now.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2013-07-14 23:36:14 -04:00
parent aedc2eddd1
commit 6c5a28255b
1 changed files with 25 additions and 11 deletions
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28
src/shared/install.c
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@ -1062,8 +1062,8 @@ static int unit_file_search(
info->path = path;
else {
if (r == -ENOENT && unit_name_is_instance(info->name)) {
/* unit file doesn't exist, however instance enablement was request */
/* we will check if it is possible to load template unit file */
/* Unit file doesn't exist, however instance enablement was requested.
* We will check if it is possible to load template unit file. */
char *template = NULL,
*template_path = NULL,
*template_dir = NULL;
@ -1074,7 +1074,7 @@ static int unit_file_search(
return -ENOMEM;
}
/* we will reuse path variable since we don't need it anymore */
/* We will reuse path variable since we don't need it anymore. */
template_dir = path;
*(strrchr(path, '/') + 1) = '\0';
@ -1085,7 +1085,7 @@ static int unit_file_search(
return -ENOMEM;
}
/* let's try to load template unit */
/* Let's try to load template unit. */
r = unit_file_load(c, info, template_path, allow_symlink);
if (r >= 0) {
info->path = strdup(template_path);
@ -1425,16 +1425,30 @@ static int install_context_mark_for_removal(
r += q;
if (unit_name_is_instance(i->name)) {
char *unit_file = NULL;
char *unit_file;
if (i->path) {
unit_file = path_get_file_name(i->path);
if (unit_name_is_instance(unit_file))
/* unit file named as instance exists, thus all symlinks pointing to it, will be removed */
/* unit file named as instance exists, thus all symlinks
* pointing to it will be removed */
q = mark_symlink_for_removal(remove_symlinks_to, i->name);
else
/* does not exist, thus we will mark for removal symlinks to template unit file */
/* does not exist, thus we will mark for removal symlinks
* to template unit file */
q = mark_symlink_for_removal(remove_symlinks_to, unit_file);
} else {
/* If i->path is not set, it means that we didn't actually find
* the unit file. But we can still remove symlinks to the
* nonexistent template. */
unit_file = unit_name_template(i->name);
if (!unit_file)
return log_oom();
q = mark_symlink_for_removal(remove_symlinks_to, unit_file);
free(unit_file);
}
} else
q = mark_symlink_for_removal(remove_symlinks_to, i->name);