Module Name: src
Committed By: maxv
Date: Mon Apr 20 16:32:03 UTC 2020
Modified Files:
src/sys/kern: kern_proc.c
Log Message:
Add three KASSERTs, to detect refcount bugs.
This narrows down an unknown bug in some place near, that has manifested
itself in various forms (use-after-frees, uninit accesses, page faults,
segmentation faults), all pointed out by syzbot.
The first KASSERT in fixjobc() fires when the bug is encountered.
To generate a diff of this commit:
cvs rdiff -u -r1.244 -r1.245 src/sys/kern/kern_proc.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/kern_proc.c
diff -u src/sys/kern/kern_proc.c:1.244 src/sys/kern/kern_proc.c:1.245
--- src/sys/kern/kern_proc.c:1.244 Sun Apr 19 20:31:59 2020
+++ src/sys/kern/kern_proc.c Mon Apr 20 16:32:03 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_proc.c,v 1.244 2020/04/19 20:31:59 thorpej Exp $ */
+/* $NetBSD: kern_proc.c,v 1.245 2020/04/20 16:32:03 maxv Exp $ */
/*-
* Copyright (c) 1999, 2006, 2007, 2008, 2020 The NetBSD Foundation, Inc.
@@ -62,7 +62,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_proc.c,v 1.244 2020/04/19 20:31:59 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_proc.c,v 1.245 2020/04/20 16:32:03 maxv Exp $");
#ifdef _KERNEL_OPT
#include "opt_kstack.h"
@@ -554,6 +554,7 @@ proc_sessrele(struct session *ss)
{
KASSERT(mutex_owned(proc_lock));
+ KASSERT(ss->s_count > 0);
/*
* We keep the pgrp with the same id as the session in order to
* stop a process being given the same pid. Since the pgrp holds
@@ -1181,8 +1182,11 @@ fixjobc(struct proc *p, struct pgrp *pgr
if (entering) {
pgrp->pg_jobc++;
p->p_lflag &= ~PL_ORPHANPG;
- } else if (--pgrp->pg_jobc == 0)
- orphanpg(pgrp);
+ } else {
+ KASSERT(pgrp->pg_jobc > 0);
+ if (--pgrp->pg_jobc == 0)
+ orphanpg(pgrp);
+ }
}
/*
@@ -1197,8 +1201,11 @@ fixjobc(struct proc *p, struct pgrp *pgr
if (entering) {
child->p_lflag &= ~PL_ORPHANPG;
hispgrp->pg_jobc++;
- } else if (--hispgrp->pg_jobc == 0)
- orphanpg(hispgrp);
+ } else {
+ KASSERT(hispgrp->pg_jobc > 0);
+ if (--hispgrp->pg_jobc == 0)
+ orphanpg(hispgrp);
+ }
}
}
}
