Fix undefined behaviour in datetime.time.fromisoformat() (#111982)

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).

diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index 9938ed5f8095b575962a7c9774ab6ba63aa2c6e1..cb5403e8461ff0e8972c4e1a515629fe1a11b2f8 100644 (file)
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -4630,7 +4630,7 @@ 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);