[src/trunk]: src/sys/kern fix use-after-free in config_interrupts_thread() fo...

[jdolecek <jdolecek%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/b58e042dd336
branches:  trunk
changeset: 969645:b58e042dd336
user:      jdolecek <jdolecek%NetBSD.org@localhost>
date:      Tue Feb 25 19:14:05 2020 +0000

description:
fix use-after-free in config_interrupts_thread() found by KASAN, introduced
with addition of the locking; problem pointed out by kamil@

diffstat:

 sys/kern/subr_autoconf.c |  16 +++++++++-------
 1 files changed, 9 insertions(+), 7 deletions(-)

diffs (47 lines):

diff -r e8e48a3a2e1f -r b58e042dd336 sys/kern/subr_autoconf.c
--- a/sys/kern/subr_autoconf.c  Tue Feb 25 16:24:47 2020 +0000
+++ b/sys/kern/subr_autoconf.c  Tue Feb 25 19:14:05 2020 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: subr_autoconf.c,v 1.266 2020/02/20 21:14:23 jdolecek Exp $ */
+/* $NetBSD: subr_autoconf.c,v 1.267 2020/02/25 19:14:05 jdolecek Exp $ */
 
 /*
  * Copyright (c) 1996, 2000 Christopher G. Demetriou
@@ -77,7 +77,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: subr_autoconf.c,v 1.266 2020/02/20 21:14:23 jdolecek Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_autoconf.c,v 1.267 2020/02/25 19:14:05 jdolecek Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_ddb.h"
@@ -442,21 +442,23 @@
 config_interrupts_thread(void *cookie)
 {
        struct deferred_config *dc;
+       device_t dev;
 
        mutex_enter(&config_misc_lock);
        while ((dc = TAILQ_FIRST(&interrupt_config_queue)) != NULL) {
                TAILQ_REMOVE(&interrupt_config_queue, dc, dc_queue);
                mutex_exit(&config_misc_lock);
 
-               (*dc->dc_func)(dc->dc_dev);
-               if (!device_pmf_is_registered(dc->dc_dev))
-                       aprint_debug_dev(dc->dc_dev,
+               dev = dc->dc_dev;
+               (*dc->dc_func)(dev);
+               if (!device_pmf_is_registered(dev))
+                       aprint_debug_dev(dev,
                            "WARNING: power management not supported\n");
-               config_pending_decr(dc->dc_dev);
+               config_pending_decr(dev);
                kmem_free(dc, sizeof(*dc));
 
                mutex_enter(&config_misc_lock);
-               dc->dc_dev->dv_flags &= ~DVF_ATTACH_INPROGRESS;
+               dev->dv_flags &= ~DVF_ATTACH_INPROGRESS;
        }
        mutex_exit(&config_misc_lock);