archive mirror
 help / color / mirror / Atom feed
* [devfs] Use before initialisation in devfs_mk_cdev()
@ 2003-07-16 23:53 Gergely Nagy
  2003-07-18 11:33 ` Christoph Hellwig
  0 siblings, 1 reply; 2+ messages in thread
From: Gergely Nagy @ 2003-07-16 23:53 UTC (permalink / raw)
  To: linux-kernel; +Cc: Gergely Nagy


While playing around with implementing my first linux 2.5 module, I
stumbled upon a buglet in devfs (though, if used properly, it probably
won't surface ever). The problem - as I see it - is that
devfs_mk_cdev() first checks the mode passed to it, and if it thinks
it is not a char device, it prints a warning and aborts. Now, this
printing involves the local variable `buf' (char buf[64]), which is
not initialised at that point.

The problematic code is:

int devfs_mk_cdev(dev_t dev, umode_t mode, const char *fmt, ...)
	struct devfs_entry *dir = NULL, *de;
	char buf[64];
	va_list args;
	int error, n;

	if (!S_ISCHR(mode)) {
		printk(KERN_WARNING "%s: invalide mode (%u) for %s\n",
				__FUNCTION__, mode, buf);
		return -EINVAL;

One option would be to try to initialise buf earlier, another would be
to just remove the "for %s" part, and the buf reference in the printk
(but that way, some information would be lost).

Anyways, I just noticed that when my buggy code called devfs_mk_cdev
(blah, 0, etc..) it printed garbage on module insertion, so I thought
I'd drop a notice.

Oh, this is with Linux 2.6.0-test1-mm1.

Gergely Nagy

^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, other threads:[~2003-07-18 11:18 UTC | newest]

Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2003-07-16 23:53 [devfs] Use before initialisation in devfs_mk_cdev() Gergely Nagy
2003-07-18 11:33 ` Christoph Hellwig

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).