Precedence: list
MIME-Version: 1.0
Date: Wed, 9 Apr 2014 17:16:14 -0500
Message-ID: <CAEuRe+0Ofx8v3hpCyTCPKtRJJrrxM7ZkcKkTWamhzmVw47fLzQ@mail.gmail.com>
Subject: [alpine-devel] Segfault in hwclock
From: Jeff Pohlmeyer <yetanothergeek@gmail.com>
To: Alpine <alpine-devel@lists.alpinelinux.org>
Content-Type: text/plain; charset=ISO-8859-1

The "hwclock" program from util-linux is crashing with musl.

The problem is on line 393 of util-linux-2.23.2/sys-utils/hwclock.c:

  setenv("TZ", getenv("TZUTC"), TRUE);

Apparently musl's version of setenv() doesn't like it when the second
argument is NULL.

( The crash only happens if the "TZUTC" environment variable is unset. )


Here is a simple test app:
/*********************************/
#include <stdlib.h>
int main(int argc, char*argv[]) {
  setenv("FOO",NULL,1);
  return 0;
}
/*********************************/

Compiling with gcc -Wall on ArchLinux/GNU-libc, I get a warning:

  warning: null argument where non-null required (argument 2) [-Wnonnull]

But the program doesn't crash at run time.


With Alpine/musl, there is no compile time warning, but the program crashes.


So it looks like musl's setenv() could stand to be a bit more robust,
but hwclock
really shouldn't be passing it a null, either.


 - Jeff


---
Unsubscribe:  alpine-devel+unsubscribe@lists.alpinelinux.org
Help:         alpine-devel+help@lists.alpinelinux.org
---