From: Paul Eggert <eggert@cs.ucla.edu>
Date: Tue, 14 Sep 2021 05:49:45 +0000 (-0700)
Subject: Fix subscript error with odd TZif file [BZ #28338]
X-Git-Tag: glibc-2.35~441
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=645277434a42efc547d2cac8bfede4da10b4049f;p=thirdparty%2Fglibc.git

Fix subscript error with odd TZif file [BZ #28338]

* time/tzfile.c (__tzfile_compute): Fix unlikely off-by-one bug
that accessed before start of an array when an oddball-but-valid
TZif file was queried with an unusual time_t value.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
---

diff --git a/time/tzfile.c b/time/tzfile.c
index 4377018a559..190a777152b 100644
--- a/time/tzfile.c
+++ b/time/tzfile.c
@@ -765,8 +765,7 @@ __tzfile_compute (__time64_t timer, int use_localtime,
   *leap_correct = leaps[i].change;
 
   if (timer == leaps[i].transition /* Exactly at the transition time.  */
-      && ((i == 0 && leaps[i].change > 0)
-	  || leaps[i].change > leaps[i - 1].change))
+      && (leaps[i].change > (i == 0 ? 0 : leaps[i - 1].change)))
     {
       *leap_hit = 1;
       while (i > 0