Fix undefined behaviour in datetime.time.fromisoformat() (pythonGH-111982)

Yhg1s · miss-islington · commit 13cd2bf9bd2b · 2023-11-12T00:05:22.000Z
Fix undefined behaviour in datetime.time.fromisoformat() when parsing a string without a timezone. 'tzoffset' is not assigned to by parse_isoformat_time if it returns 0, but time_fromisoformat then passes tzoffset to another function, which is undefined behaviour (even if the function in question does not use the value). (cherry picked from commit 21615f7) Co-authored-by: T. Wouters <thomas@python.org>
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
@@ -4649,7 +4649,7 @@ time_fromisoformat(PyObject *cls, PyObject *tstr) {
     }
 
     int hour = 0, minute = 0, second = 0, microsecond = 0;
-    int tzoffset, tzimicrosecond = 0;
+    int tzoffset = 0, tzimicrosecond = 0;
     int rv = parse_isoformat_time(p, len,
                                   &hour, &minute, &second, &microsecond,
                                   &tzoffset, &tzimicrosecond);

Original file line number	Diff line number	Diff line change
`@@ -4649,7 +4649,7 @@ time_fromisoformat(PyObject cls, PyObject tstr) {`
`4649`	`4649`	`}`
`4650`	`4650`
`4651`	`4651`	`int hour = 0, minute = 0, second = 0, microsecond = 0;`
`4652`		`- int tzoffset, tzimicrosecond = 0;`
	`4652`	`+ int tzoffset = 0, tzimicrosecond = 0;`
`4653`	`4653`	`int rv = parse_isoformat_time(p, len,`
`4654`	`4654`	`&hour, &minute, &second, &microsecond,`
`4655`	`4655`	`&tzoffset, &tzimicrosecond);`