Date: Tue, 20 Jun 1995 22:06:09 +0200 From: petri@ibr.cs.tu-bs.de (stefan Petri) To: FreeBSD-gnats-submit@freebsd.org, bugs@freebsd.org Subject: pci_bus_config() does not init parent pointers in device list + fix Message-ID: <199506202006.WAA00698@jupiter.ibr.cs.tu-bs.de>
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>Submitter-Id: net
>Originator: Stefan Petri
>Organization: TU Braunschweig, Inst. f. Betriebssysteme u. Rechnerverbund
>Confidential: no
>Synopsis: pci_bus_config() does not init parent pointers in device list
>Severity: serious
>Priority: medium
>Category: kern
>Release: FreeBSD 2.0.950412-SNAP i386
>Class: change-request
>Environment:
486 with PCI bus,
FreeBSD kernel with ``option DIAGNOSTIC'' enabled
>Description:
/usr/src/sys/pci.c::pci_bus_config() does not initialize the
parent pointers in the devconf list; there is also a comment
that this should be added. In the GENERIC kernel, this seems not
to be a real problem, because the freshly malloced devconf
structure almost always is pre-set with 0 resp. NULL.
However, if ``option DIAGNOSTIC'' is enabled, malloc() will
fill all memory areas with pattern 0xdeadbeef. If lsdev(8) is
invoked on such a kernel, it will result in a panic when
trying to get the descriptions for the PCI bus via sysctl(3).
>How-To-Repeat:
short version: invoke lsdev(8) on a kernel compiled with DIAGNOSTIC,
on a machine with PCI bus
long version: instrument lsdev and /sys/kern/kern_devconf.c with
printf()s, and then:
jupiter:/tmp 2 # sync;sync;sync;./lsdev+printf
Device State Description
---------- --------------- --------------------------------------------------
cpu0 Busy i486 DX4
[..]
npx0 Busy Floating-point unit
> sysctl( {6, 11, 12}, 3, dc, &size, 0, 0)
jupiter /kernel: make_devconf(name=chip unit=0 number=12 parent=0xdeadbeef
^^^^ ^^^^^^^^^^
jupiter /kernel: Fatal trap 12: page fault while in kernel mode
[..]
>Fix:
simply disabling DIAGNOSTIC would be the equivalent to wearing my
Joo Janta 200 Super-Chromatic Peril Sensitive Sunglasses, so I
suggest the following:
--- pci.c-2.0.950412-SNAP Thu Mar 23 07:14:44 1995
+++ pci.c Tue Jun 20 21:27:04 1995
@@ -551,7 +551,10 @@
pdcp -> pdc_kdc.kdc_name = dvp->pd_name;
pdcp -> pdc_kdc.kdc_unit = unit;
+ pdcp -> pdc_kdc.kdc_parent = NULL;
+
pdcp -> pdc_kdc.kdc_md.mddc_devtype = MDDT_PCI;
+ pdcp -> pdc_kdc.kdc_md.mddc_flags = 0;
pdcp -> pdc_kdc.kdc_externalize = pci_externalize;
pdcp -> pdc_kdc.kdc_internalize = pci_internalize;
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