integer overflow at dow.c157:30

[chongwick]

Description

The following code:

<?php
$date = date_create();
date_isodate_set($date, date('Y'), 1, PHP_INT_MIN);
?>

Resulted in this output:

/home/dan/php-src/ext/date/lib/dow.c:157:30: runtime error: signed integer overflow: -9223372036854775808 + -1 cannot be represented in type 'long long int'

But I expected this output instead:

PHP Version

8.4.1

Operating System

No response

[chongwick]

similar to issues #16865 and #17024
overflows at different points in this statement:
"return day + ((iw - 1) * 7) + id;"

[cmb69]

Like I've said elsewhere, I think we need to start with timelib clearly stating the preconditions (and postconditions) of the public functions. In this case something like the following might do (probably not quite correct):

 ext/date/lib/dow.c     | 6 ++++++
 ext/date/lib/timelib.h | 4 ++++
 2 files changed, 10 insertions(+)

diff --git a/ext/date/lib/dow.c b/ext/date/lib/dow.c
index c288e5db97..5ee4bd0641 100644
--- a/ext/date/lib/dow.c
+++ b/ext/date/lib/dow.c
@@ -148,6 +148,12 @@ timelib_sll timelib_daynr_from_weeknr(timelib_sll iy, timelib_sll iw, timelib_sl
 {
 	timelib_sll dow, day;
 
+	assert(id >= TIMELIB_SSL_MIN + 4 && id <= TIMELIB_SSL_MAX - 2);
+	assert(iw >= TIMELIB_SSL_MIN + 1);
+	assert(iw - 1 >= TIMELIB_SSL_MIN / 7 && iw - 1 <= TIMELIB_SSL_MAX / 7);
+	assert(!((iw - 1) * 7 >= 0 && id >= 0) || (iw - 1) * 7 <= TIMELIB_SSL_MAX - id);
+	assert(!((iw - 1) * 7 < 0 && id < 0) || (iw - 1) * 7 >= TIMELIB_SSL_MIN + id);
+
 	/* Figure out the dayofweek for y-1-1 */
 	dow = timelib_day_of_week(iy, 1, 1);
 	/* then use that to figure out the offset for day 1 of week 1 */
diff --git a/ext/date/lib/timelib.h b/ext/date/lib/timelib.h
index a2c976af7e..eae4493563 100644
--- a/ext/date/lib/timelib.h
+++ b/ext/date/lib/timelib.h
@@ -130,10 +130,14 @@ typedef uint32_t timelib_ulong;
 #if defined(_MSC_VER)
 typedef uint64_t timelib_ull;
 typedef int64_t timelib_sll;
+# define TIMELIB_SSL_MAX INT64_MAX
+# define TIMELIB_SSL_MIN INT64_MIN
 # define TIMELIB_LL_CONST(n) n ## i64
 #else
 typedef unsigned long long timelib_ull;
 typedef signed long long timelib_sll;
+# define TIMELIB_SSL_MAX LLONG_MAX
+# define TIMELIB_SSL_MIN LLONG_MIN
 # define TIMELIB_LL_CONST(n) n ## ll
 #endif

Then clients could use these preconditions to check for possible over-/underflow conditions in advance, and act accordingly (in this case php_date_isodate_set() might throw a ValueError).