kern/125030: [devfs.rules][patch] Command 'devfs ruleset 0' causes panic

[Mateusz Guzik]

>Number:         125030
>Category:       kern
>Synopsis:       [devfs.rules][patch] Command 'devfs ruleset 0' causes panic
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Jun 26 22:50:01 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     Mateusz Guzik
>Release:        8.0-CURRENT
>Organization:
>Environment:
FreeBSD eternal 8.0-CURRENT FreeBSD 8.0-CURRENT #35: Fri Jun 27 00:10:53 CEST 2008     f at eternal:/usr/obj/usr/src/sys/ETERNAL  i386

>Description:
Function devfs_ruleset_use() doesn't treat rsnum = 0 as a special case and calls devfs_ruleset_create() to create it, causing panic. 
>How-To-Repeat:
Run `devfs ruleset 0'.
>Fix:
Patch is attached.

Patch attached with submission follows:

--- sys/fs/devfs/devfs_rule.c.orig	2008-06-26 23:14:23.000000000 +0200
+++ sys/fs/devfs/devfs_rule.c	2008-06-26 23:36:59.000000000 +0200
@@ -739,10 +739,15 @@
 		cds = devfs_ruleset_bynum(dm->dm_ruleset);
 		--cds->ds_refcount;
 		devfs_ruleset_reap(cds);
 	}
 
+	if (rsnum == 0) {
+		dm->dm_ruleset = 0;
+		return (0);
+	}
+
 	ds = devfs_ruleset_bynum(rsnum);
 	if (ds == NULL)
 		ds = devfs_ruleset_create(rsnum);
 	/* These should probably be made atomic somehow. */
 	++ds->ds_refcount;


>Release-Note:
>Audit-Trail:
>Unformatted: