Valgrind error "Conditional jump or move depends on uninitialised value" on 64-bit

Oct. 5, 2010

I'm seeing two problems in localtime.c:

1. When I compile localtime.c using gcc 4.1.2 for 32-bit, I get following 
warning:

$ gcc -m32 -g -c -o localtime.o localtime.c
localtime.c: In function âdiffer_by_repeatâ:
localtime.c:326: warning: comparison is always false due to limited range of 
data type

2. valgrind reports following error for some timezones (only when localtime.c 
is compiled as 

64-bit binary, it does not happen when compiled as 32-bit binary):

==26671== Conditional jump or move depends on uninitialised value(s)
==26671==    at 0x401CDA: typesequiv (localtime.c:588)
==26671==    by 0x401B85: tzload (localtime.c:562)
==26671==    by 0x405553: tz_validate (localtime.c:2017)
==26671==    by 0x40560D: main (localtime.c:2040)

One can reproduce it using following valgrind command and patch:

valgrind -v --tool=memcheck --leak-check=full --leak-resolution=med --show-
reachable=yes 

--error-limit=no --workaround-gcc296-bugs=yes --run-libc-freeres=no --log-
file=valgrind-tzvalid 

./tzvalid /<path/to/my/zoneinfo/EST5EDT>

NOTE: I can consistently reproduce it for EST5EDT timezone and I don't get 
this error for 

GMT.

Patch for localtime.c for reproducing above error:

--- org/localtime.c     2010-08-16 16:27:05.000000000 +0530
+++ localtime.c 2010-10-01 17:34:45.999089000 +0530
@@ -2004,6 +2004,47 @@

 #endif /* defined CMUCS */

+static int
+tz_validate(const char * name)
+{
+       struct state    state = {0};
+       time_t                  now;
+       struct tm               tm;
+
+       time(&now);
+       tzload(gmt, &state, TRUE);
+       if (0 == tzload(name, &state, TRUE)) {
+               localsub(&now, 0L, &tm);
+               return TRUE;
+       }
+       if (0 == tzparse(name, &state, FALSE)) {
+               localsub(&now, 0L, &tm);
+               return TRUE;
+       }
+       return FALSE;
+}
+
+/*
+ *  Compile it simply as "$gcc -m64 -g -o tzvalid localtime.c"
+ */
+int main(int argc, char ** argv) {
+
+       if (argc != 2) {
+               printf("Usage: ./tzvalid <timezone_file_path>\n");
+               return 2;
+       }
+
+       char * tz = argv[1];
+
+       if (tz_validate(tz)) {
+               printf("timezone %s is valid\n", tz);
+               return 0;
+       } else {
+               printf("timezone %s is not valid\n", tz);
+               return 1;
+       }
+}
+
 /*
 ** XXX--is the below the right way to conditionalize??
 */

Thanks in advance,
Ravindra

    