From 759e51ebe765068c458a7a0c34f19eaebe705075 Mon Sep 17 00:00:00 2001
From: mvs <mvs@openbsd.org>
Date: Thu, 18 May 2023 10:23:19 +0000
Subject: [PATCH] Backout sysctl(2) unlocking. Lock order issue was triggered
 in UVM layer.

---
 sys/kern/kern_sysctl.c   | 17 +++++------------
 sys/kern/syscalls.master |  4 ++--
 sys/kern/uipc_domain.c   | 34 +++++++++++-----------------------
 3 files changed, 18 insertions(+), 37 deletions(-)

diff --git a/sys/kern/kern_sysctl.c b/sys/kern/kern_sysctl.c
index 7c19cf363b8..f63fc7cc420 100644
--- a/sys/kern/kern_sysctl.c
+++ b/sys/kern/kern_sysctl.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_sysctl.c,v 1.413 2023/05/17 22:12:51 kettenis Exp $	*/
+/*	$OpenBSD: kern_sysctl.c,v 1.414 2023/05/18 10:23:19 mvs Exp $	*/
 /*	$NetBSD: kern_sysctl.c,v 1.17 1996/05/20 17:49:05 mrg Exp $	*/
 
 /*-
@@ -169,7 +169,7 @@ sys_sysctl(struct proc *p, void *v, register_t *retval)
 		syscallarg(void *) new;
 		syscallarg(size_t) newlen;
 	} */ *uap = v;
-	int error, dokernellock = 1, dolock = 1;
+	int error, dolock = 1;
 	size_t savelen = 0, oldlen = 0;
 	sysctlfn *fn;
 	int name[CTL_MAXNAME];
@@ -204,7 +204,6 @@ sys_sysctl(struct proc *p, void *v, register_t *retval)
 		break;
 	case CTL_NET:
 		fn = net_sysctl;
-		dokernellock = 0;
 		break;
 	case CTL_FS:
 		fn = fs_sysctl;
@@ -232,22 +231,19 @@ sys_sysctl(struct proc *p, void *v, register_t *retval)
 	if (SCARG(uap, oldlenp) &&
 	    (error = copyin(SCARG(uap, oldlenp), &oldlen, sizeof(oldlen))))
 		return (error);
-	if (dokernellock)
-		KERNEL_LOCK();
 	if (SCARG(uap, old) != NULL) {
 		if ((error = rw_enter(&sysctl_lock, RW_WRITE|RW_INTR)) != 0)
-			goto unlock;
+			return (error);
 		if (dolock) {
 			if (atop(oldlen) > uvmexp.wiredmax - uvmexp.wired) {
 				rw_exit_write(&sysctl_lock);
-				error = ENOMEM;
-				goto unlock;
+				return (ENOMEM);
 			}
 			error = uvm_vslock(p, SCARG(uap, old), oldlen,
 			    PROT_READ | PROT_WRITE);
 			if (error) {
 				rw_exit_write(&sysctl_lock);
-				goto unlock;
+				return (error);
 			}
 		}
 		savelen = oldlen;
@@ -259,9 +255,6 @@ sys_sysctl(struct proc *p, void *v, register_t *retval)
 			uvm_vsunlock(p, SCARG(uap, old), savelen);
 		rw_exit_write(&sysctl_lock);
 	}
-unlock:
-	if (dokernellock)
-		KERNEL_UNLOCK();
 	if (error)
 		return (error);
 	if (SCARG(uap, oldlenp))
diff --git a/sys/kern/syscalls.master b/sys/kern/syscalls.master
index 3faf5dde4a5..34bef2ba6a0 100644
--- a/sys/kern/syscalls.master
+++ b/sys/kern/syscalls.master
@@ -1,4 +1,4 @@
-;	$OpenBSD: syscalls.master,v 1.247 2023/05/04 09:40:36 mvs Exp $
+;	$OpenBSD: syscalls.master,v 1.248 2023/05/18 10:23:19 mvs Exp $
 ;	$NetBSD: syscalls.master,v 1.32 1996/04/23 10:24:21 mycroft Exp $
 
 ;	@(#)syscalls.master	8.2 (Berkeley) 1/13/94
@@ -361,7 +361,7 @@
 199	OBSOL		pad_lseek
 200	OBSOL		pad_truncate
 201	OBSOL		pad_ftruncate
-202	STD NOLOCK	{ int sys_sysctl(const int *name, u_int namelen, \
+202	STD		{ int sys_sysctl(const int *name, u_int namelen, \
 			    void *old, size_t *oldlenp, void *new, \
 			    size_t newlen); }
 203	STD		{ int sys_mlock(const void *addr, size_t len); }
diff --git a/sys/kern/uipc_domain.c b/sys/kern/uipc_domain.c
index ba9a69b96bd..78ae0900a00 100644
--- a/sys/kern/uipc_domain.c
+++ b/sys/kern/uipc_domain.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uipc_domain.c,v 1.63 2023/05/18 09:59:43 mvs Exp $	*/
+/*	$OpenBSD: uipc_domain.c,v 1.64 2023/05/18 10:23:19 mvs Exp $	*/
 /*	$NetBSD: uipc_domain.c,v 1.14 1996/02/09 19:00:44 christos Exp $	*/
 
 /*
@@ -188,7 +188,7 @@ net_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
 {
 	const struct domain *dp;
 	const struct protosw *pr;
-	int error, family, protocol;
+	int family, protocol;
 
 	/*
 	 * All sysctl names at this level are nonterminal.
@@ -213,13 +213,9 @@ net_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
 		    newp, newlen));
 #endif
 #if NPFLOW > 0
-	if (family == PF_PFLOW) {
-		KERNEL_LOCK();
-		error = pflow_sysctl(name + 1, namelen - 1, oldp, oldlenp,
-		    newp, newlen);
-		KERNEL_UNLOCK();
-		return (error);
-	}
+	if (family == PF_PFLOW)
+		return (pflow_sysctl(name + 1, namelen - 1, oldp, oldlenp,
+		    newp, newlen));
 #endif
 #ifdef PIPEX
 	if (family == PF_PIPEX)
@@ -227,13 +223,9 @@ net_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
 		    newp, newlen));
 #endif
 #ifdef MPLS
-	if (family == PF_MPLS) {
-		KERNEL_LOCK();
-		error = mpls_sysctl(name + 1, namelen - 1, oldp, oldlenp,
-		    newp, newlen);
-		KERNEL_UNLOCK();
-		return (error);
-	}
+	if (family == PF_MPLS)
+		return (mpls_sysctl(name + 1, namelen - 1, oldp, oldlenp,
+		    newp, newlen));
 #endif
 	dp = pffinddomain(family);
 	if (dp == NULL)
@@ -243,13 +235,9 @@ net_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
 		return (EISDIR);		/* overloaded */
 	protocol = name[1];
 	for (pr = dp->dom_protosw; pr < dp->dom_protoswNPROTOSW; pr++)
-		if (pr->pr_protocol == protocol && pr->pr_sysctl) {
-			KERNEL_LOCK();
-			error = (*pr->pr_sysctl)(name + 2, namelen - 2,
-			    oldp, oldlenp, newp, newlen);
-			KERNEL_UNLOCK();
-			return (error);
-		}
+		if (pr->pr_protocol == protocol && pr->pr_sysctl)
+			return ((*pr->pr_sysctl)(name + 2, namelen - 2,
+			    oldp, oldlenp, newp, newlen));
 	return (ENOPROTOOPT);
 }
 
-- 
2.20.1