Date: Thu, 21 May 2009 12:16:26 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-amd64@freebsd.org Cc: FreeBSD-gnats-submit@freebsd.org, Emil Mikulic <emikulic@gmail.com> Subject: Re: amd64/134786: [patch] vfs.bufspace sysctl wideness on amd64 Message-ID: <200905211216.26962.jhb@freebsd.org> In-Reply-To: <20090521144825.5E65F5C40@ppp154-240.static.internode.on.net> References: <20090521144825.5E65F5C40@ppp154-240.static.internode.on.net>
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On Thursday 21 May 2009 10:48:25 am Emil Mikulic wrote:
>
> >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));
Hummm. I guess that is correct, though that is a bit odd.
--
John Baldwin
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