amd64/134786: [patch] vfs.bufspace sysctl wideness on amd64

[Emil Mikulic]

>Number:         134786
>Category:       amd64
>Synopsis:       [patch] vfs.bufspace sysctl wideness on amd64
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-amd64
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu May 21 14:50:04 UTC 2009
>Closed-Date:
>Last-Modified:
>Originator:     Emil Mikulic
>Release:        FreeBSD 8-CURRENT
>Organization:
>Environment:
>Description:

On amd64, providing a 64-bit buffer to get the vfs.bufspace sysctl will
return a 64-bit (long) quantity, but providing a *larger* buffer will
only yield a 32-bit (int) quantity.

>How-To-Repeat:

len = 8;
sysctlbyname("vfs.bufspace", &buf, &len, NULL, 0);
/* len is still 8 */

len = 10;
sysctlbyname("vfs.bufspace", &buf, &len, NULL, 0);
/* len is 4! */

>Fix:

--- sys/kern/vfs_bio.c	2009-04-17 10:01:39.000000000 +0000
+++ sys/kern/vfs_bio.c.2	2009-05-09 09:27:16.000000000 +0000
@@ -288,15 +288,15 @@
     defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
 static int
 sysctl_bufspace(SYSCTL_HANDLER_ARGS)
 {
 	long lvalue;
 	int ivalue;
 
-	if (sizeof(int) == sizeof(long) || req->oldlen == sizeof(long))
+	if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long))
 		return (sysctl_handle_long(oidp, arg1, arg2, req));
 	lvalue = *(long *)arg1;
 	if (lvalue > INT_MAX)
 		/* On overflow, still write out a long to trigger ENOMEM. */
 		return (sysctl_handle_long(oidp, &lvalue, 0, req));
 	ivalue = lvalue;
 	return (sysctl_handle_int(oidp, &ivalue, 0, req));
>Release-Note:
>Audit-Trail:
>Unformatted: