Re: 2.6.18-rc1 bttv modprobe null pointer dereference

[Andrew Morton <akpm@osdl.org>]

On Thu, 6 Jul 2006 22:19:09 -0700
"Bret Towe" <magnade@gmail.com> wrote:

> > > Code: 4c 8b bf 48 01 00 00 48 8b bf c0 00 00 00 8b 5e 10 48 81 c7
> > > RIP  [<ffffffff802f1f9b>] sysfs_add_file+0x2b/0xb0
> > >  RSP <ffff81002ac71c28>
> > > CR2: 0000000000000149
> >
> > There don't seem to have been significant changes in bttv-driver.c for some
> > time, and we're seeing a few reports like this.  I'm suspecting that either
> > a sysfs/driver-core change was wrong, or previously wrong driver behaviour
> > is now causing oopses.
> >
> > And Mauro is offline until July 12.
> >
> > Can you send the .config please?
> 
> of course

I spent ten minutes and got lost.  I suspect videodev's class_device
handling is wrong, but I fail to spot it.

This might tell us something.

--- a/drivers/media/video/videodev.c~videodev-check-return-values
+++ a/drivers/media/video/videodev.c
@@ -1512,6 +1512,7 @@ int video_register_device(struct video_d
 	int i=0;
 	int base;
 	int end;
+	int ret;
 	char *name_base;
 
 	switch(type)
@@ -1571,9 +1572,19 @@ int video_register_device(struct video_d
 	vfd->class_dev.class       = &video_class;
 	vfd->class_dev.devt        = MKDEV(VIDEO_MAJOR, vfd->minor);
 	sprintf(vfd->class_dev.class_id, "%s%d", name_base, i - base);
-	class_device_register(&vfd->class_dev);
-	class_device_create_file(&vfd->class_dev,
-				&class_device_attr_name);
+	ret = class_device_register(&vfd->class_dev);
+	if (ret < 0) {
+		printk(KERN_ERR "%s: class_device_register() returned %d\n",
+			__FUNCTION__, ret);
+	} else {
+		ret = class_device_create_file(&vfd->class_dev,
+					&class_device_attr_name);
+		if (ret < 0) {
+			printk(KERN_ERR "%s: class_device_create_file() "
+					"returned %d\n", __FUNCTION__, ret);
+			class_device_unregister(&vfd->class_dev);
+		}
+	}
 
 #if 1
 	/* needed until all drivers are fixed */
@@ -1582,7 +1593,7 @@ int video_register_device(struct video_d
 		       "Please fix your driver for proper sysfs support, see "
 		       "http://lwn.net/Articles/36850/\n", vfd->name);
 #endif
-	return 0;
+	return ret;
 }
 
 /**
_