diff options
authorRich Felker <>2014-04-22 20:09:56 -0400
committerRich Felker <>2014-04-22 20:09:56 -0400
commitc3d9d172b1fcd56c4d356798f4e3b4653076bcc3 (patch)
parent0f2315b4af1c58cbfb7c7f9da69b495cd146cc18 (diff)
perform minimal sanity checks on zoneinfo files loaded via TZ variable
previously, setting TZ to the pathname of a file which was not a valid zoneinfo file would usually cause programs using local time zone based operations to crash. the new code checks the file size and magic at the beginning of the file, which seems sufficient to prevent accidental misconfiguration from causing crashes. attempting to make fully-robust validation would be futile unless we wanted to drop use of mmap (shared zoneinfo) and instead read it into a local buffer, since such validation would be subject to race conditions with modification of the file.
1 files changed, 5 insertions, 0 deletions
diff --git a/src/time/__tz.c b/src/time/__tz.c
index 93d59e8d..6d7173cf 100644
--- a/src/time/__tz.c
+++ b/src/time/__tz.c
@@ -168,6 +168,11 @@ static void do_tzset()
if (!map) s = __gmt;
+ if (map && (map_size < 44 || memcmp(map, "TZif", 4))) {
+ __munmap((void *)map, map_size);
+ map = 0;
+ s = __gmt;
+ }
zi = map;
if (map) {