Mercurial > gnulib
diff lib/mktime.c @ 39814:6cbd05e63545
mktime: fix unlikely race+overflow bug
Problem reported by Alexandre Oliva in:
https://sourceware.org/bugzilla/show_bug.cgi?id=16346
* lib/mktime.c (__mktime_internal): Access *OFFSET only once,
to avoid an unlikely race if the compiler delays a load and
if this cascades into a signed integer overflow.
| author | Paul Eggert <eggert@cs.ucla.edu> |
|---|---|
| date | Sun, 02 Sep 2018 02:53:31 -0700 |
| parents | a3f5f4c1daee |
| children | a5c8c624b444 |
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--- a/lib/mktime.c Fri Aug 31 18:02:48 2018 -0700 +++ b/lib/mktime.c Sun Sep 02 02:53:31 2018 -0700 @@ -394,6 +394,7 @@ long_int lmday = mday; long_int yday = mon_yday + lmday; + mktime_offset_t off = *offset; int negative_offset_guess; int sec_requested = sec; @@ -411,7 +412,7 @@ /* Invert CONVERT by probing. First assume the same offset as last time. */ - INT_SUBTRACT_WRAPV (0, *offset, &negative_offset_guess); + INT_SUBTRACT_WRAPV (0, off, &negative_offset_guess); t0 = ydhms_diff (year, yday, hour, min, sec, EPOCH_YEAR - TM_YEAR_BASE, 0, 0, 0, negative_offset_guess);