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Merge pull request #19075 from keszybz/calendarspec-loop

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Fix infinite loop in calendarspec calculation when timezone has negative DST save value
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
2021-03-23 09:06:16 +01:00
committed by GitHub
parent e6fda8f675 129cb6e249
commit ca83c7f88c
3 changed files with 73 additions and 47 deletions
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src/shared/calendarspec.c
+47 -21
View File
@@ -1101,7 +1101,7 @@ int calendar_spec_from_string(const char *p, CalendarSpec **spec) {
return 0;
}
static int find_end_of_month(struct tm *tm, bool utc, int day) {
static int find_end_of_month(const struct tm *tm, bool utc, int day) {
struct tm t = *tm;
t.tm_mon++;
@@ -1114,28 +1114,39 @@ static int find_end_of_month(struct tm *tm, bool utc, int day) {
return t.tm_mday;
}
static int find_matching_component(const CalendarSpec *spec, const CalendarComponent *c,
struct tm *tm, int *val) {
const CalendarComponent *p = c;
int start, stop, d = -1;
static int find_matching_component(
const CalendarSpec *spec,
const CalendarComponent *c,
const struct tm *tm, /* tm is only used for end-of-month calculations */
int *val) {
int d = -1, r;
bool d_set = false;
int r;
assert(val);
/* Finds the *earliest* matching time specified by one of the CalendarCompoment items in chain c.
* If no matches can be found, returns -ENOENT.
* Otherwise, updates *val to the matching time. 1 is returned if *val was changed, 0 otherwise.
*/
if (!c)
return 0;
while (c) {
start = c->start;
stop = c->stop;
bool end_of_month = spec->end_of_month && c == spec->day;
if (spec->end_of_month && p == spec->day) {
start = find_end_of_month(tm, spec->utc, start);
stop = find_end_of_month(tm, spec->utc, stop);
while (c) {
int start, stop;
if (end_of_month) {
start = find_end_of_month(tm, spec->utc, c->start);
stop = find_end_of_month(tm, spec->utc, c->stop);
if (stop > 0)
SWAP_TWO(start, stop);
} else {
start = c->start;
stop = c->stop;
}
if (start >= *val) {
@@ -1184,15 +1195,18 @@ static int tm_within_bounds(struct tm *tm, bool utc) {
return negative_errno();
/* Did any normalization take place? If so, it was out of bounds before */
bool good = t.tm_year == tm->tm_year &&
t.tm_mon == tm->tm_mon &&
t.tm_mday == tm->tm_mday &&
t.tm_hour == tm->tm_hour &&
t.tm_min == tm->tm_min &&
t.tm_sec == tm->tm_sec;
if (!good)
int cmp = CMP(t.tm_year, tm->tm_year) ?:
CMP(t.tm_mon, tm->tm_mon) ?:
CMP(t.tm_mday, tm->tm_mday) ?:
CMP(t.tm_hour, tm->tm_hour) ?:
CMP(t.tm_min, tm->tm_min) ?:
CMP(t.tm_sec, tm->tm_sec);
if (cmp < 0)
return -EDEADLK; /* Refuse to go backward */
if (cmp > 0)
*tm = t;
return good;
return cmp == 0;
}
static bool matches_weekday(int weekdays_bits, const struct tm *tm, bool utc) {
@@ -1210,6 +1224,10 @@ static bool matches_weekday(int weekdays_bits, const struct tm *tm, bool utc) {
return (weekdays_bits & (1 << k));
}
/* A safety valve: if we get stuck in the calculation, return an error.
* C.f. https://bugzilla.redhat.com/show_bug.cgi?id=1941335. */
#define MAX_CALENDAR_ITERATIONS 1000
static int find_next(const CalendarSpec *spec, struct tm *tm, usec_t *usec) {
struct tm c;
int tm_usec;
@@ -1223,7 +1241,7 @@ static int find_next(const CalendarSpec *spec, struct tm *tm, usec_t *usec) {
c = *tm;
tm_usec = *usec;
for (;;) {
for (unsigned iteration = 0; iteration < MAX_CALENDAR_ITERATIONS; iteration++) {
/* Normalize the current date */
(void) mktime_or_timegm(&c, spec->utc);
c.tm_isdst = spec->dst;
@@ -1320,6 +1338,14 @@ static int find_next(const CalendarSpec *spec, struct tm *tm, usec_t *usec) {
*usec = tm_usec;
return 0;
}
/* It seems we entered an infinite loop. Let's gracefully return an error instead of hanging or
* aborting. This code is also exercised when timers.target is brought up during early boot, so
* aborting here is problematic and hard to diagnose for users. */
_cleanup_free_ char *s = NULL;
(void) calendar_spec_to_string(spec, &s);
return log_warning_errno(SYNTHETIC_ERRNO(EDEADLK),
"Infinite loop in calendar calculation: %s", strna(s));
}
static int calendar_spec_next_usec_impl(const CalendarSpec *spec, usec_t usec, usec_t *ret_next) {
src/test/test-calendarspec.c
+25 -26
View File
@@ -2,11 +2,11 @@
#include "alloc-util.h"
#include "calendarspec.h"
#include "env-util.h"
#include "errno-util.h"
#include "string-util.h"
#include "util.h"
static void test_one(const char *input, const char *output) {
static void _test_one(int line, const char *input, const char *output) {
CalendarSpec *c;
_cleanup_free_ char *p = NULL, *q = NULL;
usec_t u;
@@ -16,13 +16,13 @@ static void test_one(const char *input, const char *output) {
assert_se(calendar_spec_from_string(input, &c) >= 0);
assert_se(calendar_spec_to_string(c, &p) >= 0);
printf("\"%s\" → \"%s\"\n", input, p);
log_info("line %d: \"%s\" → \"%s\"", line, input, p);
assert_se(streq(p, output));
u = now(CLOCK_REALTIME);
r = calendar_spec_next_usec(c, u, &u);
printf("Next: %s\n", r < 0 ? strerror_safe(r) : format_timestamp(buf, sizeof(buf), u));
log_info("Next: %s", r < 0 ? strerror_safe(r) : format_timestamp(buf, sizeof buf, u));
calendar_spec_free(c);
assert_se(calendar_spec_from_string(p, &c) >= 0);
@@ -31,8 +31,9 @@ static void test_one(const char *input, const char *output) {
assert_se(streq(q, p));
}
#define test_one(input, output) _test_one(__LINE__, input, output)
static void test_next(const char *input, const char *new_tz, usec_t after, usec_t expect) {
static void _test_next(int line, const char *input, const char *new_tz, usec_t after, usec_t expect) {
CalendarSpec *c;
usec_t u;
char *old_tz;
@@ -43,22 +44,19 @@ static void test_next(const char *input, const char *new_tz, usec_t after, usec_
if (old_tz)
old_tz = strdupa(old_tz);
if (new_tz) {
char *colon_tz;
if (!isempty(new_tz))
new_tz = strjoina(":", new_tz);
colon_tz = strjoina(":", new_tz);
assert_se(setenv("TZ", colon_tz, 1) >= 0);
} else
assert_se(unsetenv("TZ") >= 0);
assert_se(set_unset_env("TZ", new_tz, true) == 0);
tzset();
assert_se(calendar_spec_from_string(input, &c) >= 0);
printf("\"%s\"\n", input);
log_info("line %d: \"%s\" new_tz=%s", line, input, strnull(new_tz));
u = after;
r = calendar_spec_next_usec(c, after, &u);
printf("At: %s\n", r < 0 ? strerror_safe(r) : format_timestamp_style(buf, sizeof buf, u, TIMESTAMP_US));
log_info("At: %s", r < 0 ? strerror_safe(r) : format_timestamp_style(buf, sizeof buf, u, TIMESTAMP_US));
if (expect != USEC_INFINITY)
assert_se(r >= 0 && u == expect);
else
@@ -66,12 +64,10 @@ static void test_next(const char *input, const char *new_tz, usec_t after, usec_
calendar_spec_free(c);
if (old_tz)
assert_se(setenv("TZ", old_tz, 1) >= 0);
else
assert_se(unsetenv("TZ") >= 0);
assert_se(set_unset_env("TZ", old_tz, true) == 0);
tzset();
}
#define test_next(input, new_tz, after, expect) _test_next(__LINE__, input,new_tz,after,expect)
static void test_timestamp(void) {
char buf[FORMAT_TIMESTAMP_MAX];
@@ -83,12 +79,12 @@ static void test_timestamp(void) {
x = now(CLOCK_REALTIME);
assert_se(format_timestamp_style(buf, sizeof(buf), x, TIMESTAMP_US));
printf("%s\n", buf);
assert_se(format_timestamp_style(buf, sizeof buf, x, TIMESTAMP_US));
log_info("%s", buf);
assert_se(calendar_spec_from_string(buf, &c) >= 0);
assert_se(calendar_spec_to_string(c, &t) >= 0);
calendar_spec_free(c);
printf("%s\n", t);
log_info("%s", t);
assert_se(parse_timestamp(t, &y) >= 0);
assert_se(y == x);
@@ -104,11 +100,11 @@ static void test_hourly_bug_4031(void) {
n = now(CLOCK_REALTIME);
assert_se((r = calendar_spec_next_usec(c, n, &u)) >= 0);
printf("Now: %s (%"PRIu64")\n", format_timestamp_style(buf, sizeof buf, n, TIMESTAMP_US), n);
printf("Next hourly: %s (%"PRIu64")\n", r < 0 ? strerror_safe(r) : format_timestamp_style(buf, sizeof buf, u, TIMESTAMP_US), u);
log_info("Now: %s (%"PRIu64")", format_timestamp_style(buf, sizeof buf, n, TIMESTAMP_US), n);
log_info("Next hourly: %s (%"PRIu64")", r < 0 ? strerror_safe(r) : format_timestamp_style(buf, sizeof buf, u, TIMESTAMP_US), u);
assert_se((r = calendar_spec_next_usec(c, u, &w)) >= 0);
printf("Next hourly: %s (%"PRIu64")\n", r < 0 ? strerror_safe(r) : format_timestamp_style(zaf, sizeof zaf, w, TIMESTAMP_US), w);
log_info("Next hourly: %s (%"PRIu64")", r < 0 ? strerror_safe(r) : format_timestamp_style(zaf, sizeof zaf, w, TIMESTAMP_US), w);
assert_se(n < u);
assert_se(u <= n + USEC_PER_HOUR);
@@ -209,15 +205,18 @@ int main(int argc, char* argv[]) {
test_next("2017-08-06 9..17/2:00 UTC", "", 1502029800000000, 1502031600000000);
test_next("2016-12-* 3..21/6:00 UTC", "", 1482613200000001, 1482634800000000);
test_next("2017-09-24 03:30:00 Pacific/Auckland", "", 12345, 1506177000000000);
// Due to daylight saving time - 2017-09-24 02:30:00 does not exist
/* Due to daylight saving time - 2017-09-24 02:30:00 does not exist */
test_next("2017-09-24 02:30:00 Pacific/Auckland", "", 12345, -1);
test_next("2017-04-02 02:30:00 Pacific/Auckland", "", 12345, 1491053400000000);
// Confirm that even though it's a time change here (backward) 02:30 happens only once
/* Confirm that even though it's a time change here (backward) 02:30 happens only once */
test_next("2017-04-02 02:30:00 Pacific/Auckland", "", 1491053400000000, -1);
test_next("2017-04-02 03:30:00 Pacific/Auckland", "", 12345, 1491060600000000);
// Confirm that timezones in the Spec work regardless of current timezone
/* Confirm that timezones in the Spec work regardless of current timezone */
test_next("2017-09-09 20:42:00 Pacific/Auckland", "", 12345, 1504946520000000);
test_next("2017-09-09 20:42:00 Pacific/Auckland", "EET", 12345, 1504946520000000);
/* Check that we don't start looping if mktime() moves us backwards */
test_next("Sun *-*-* 01:00:00 Europe/Dublin", "", 1616412478000000, 1617494400000000);
test_next("Sun *-*-* 01:00:00 Europe/Dublin", "IST", 1616412478000000, 1617494400000000);
assert_se(calendar_spec_from_string("test", &c) < 0);
assert_se(calendar_spec_from_string(" utc", &c) < 0);
test/test-functions
+1
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@@ -1340,6 +1340,7 @@ install_zoneinfo() {
inst_any /usr/share/zoneinfo/Asia/Vladivostok
inst_any /usr/share/zoneinfo/Australia/Sydney
inst_any /usr/share/zoneinfo/Europe/Berlin
inst_any /usr/share/zoneinfo/Europe/Dublin
inst_any /usr/share/zoneinfo/Europe/Kiev
inst_any /usr/share/zoneinfo/Pacific/Auckland
inst_any /usr/share/zoneinfo/Pacific/Honolulu