alpine 3.6
race weakness #27

5

Weakness Breakdown


Definition:

A race condition exists when parallel code accesses shared data without proper coordination. An attack that uses a race-condition weakness takes advantage of the unsafe data access to manipulate how one of the parallel sections of code reacts. Even though each process runs as intended, the outcome is unexpected. For example, consider a bank service that depends on an encryption key that it reads from a known location. An independent cryptography service is responsible for generating the key and placing it where the bank is expected to read it in a timely manner. If the bank and cryptography services do not coordinate with each other, then the bank may read a blank encryption key before cryptography writes the key to the location. This can effectively turn off all encryption for the bank without either service, or the administrator, knowing that something has gone wrong.

Warning code(s):

This accepts filename arguments; if an attacker can move those files, a race condition results..

File Name:

libgsf/src/libgsf-1.14.41/gsf/gsf-output-stdio.c

Context:

The highlighted line of code below is the trigger point of this particular Alpine 3.6 race weakness.

 #endif
#endif

#ifdef G_OS_WIN32
	/* Win32's rename does not unlink the target.  */
	goto unlink_and_retry;
#endif

done:
	return result;

unlink_and_retry:
	(void)g_unlink (newfilename);
	result = g_rename (oldfilename, newfilename);
	goto done;
}

#ifdef HAVE_CHOWN
static int
chown_wrapper (const char *filename, uid_t owner, gid_t group)
{
#ifdef HAVE_G_CHOWN
	return g_chown (filename, owner, group);
#else
	return chown (filename, owner, group);
#endif
}
#endif

#define GSF_MAX_LINK_LEVEL 256

/* Calls g_file_read_link() until we find a real filename. */
static char *
follow_symlinks (char const *filename, GError **error)
{
	gchar *followed_filename, *link;
	gint link_count = 0;

	g_return_val_if_fail (filename != NULL, NULL);

	followed_filename = g_strdup (filename);

	while ((link = g_file_read_link (followed_filename, NULL)) != NULL &&
	  ++link_count <= GSF_MAX_LINK_LEVEL) {
		if (g_path_is_absolute (link)) {
			g_free (followed_filename);
			followed_filename = link;
		} else {
			/* If the linkname is not an absolute path name, append
			 * it to the directory name of the followed filename.  E.g. 

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