From: mpi <mpi@openbsd.org>
Date: Fri, 17 Dec 2021 14:18:15 +0000 (+0000)
Subject: Do not try to unlock a NULL object.
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=f08b8e936de962e196a0ac3cccc2fd86ce3f0f30;p=openbsd

Do not try to unlock a NULL object.

Fix a NULL dereference introduced in previous, reported by anton@ and
Benjamin Baier.

Reported-by: syzbot+c172bd335801b67e515b@syzkaller.appspotmail.com
---

diff --git a/sys/uvm/uvm_fault.c b/sys/uvm/uvm_fault.c
index 4cd2efea1ec..dd709eb7aad 100644
--- a/sys/uvm/uvm_fault.c
+++ b/sys/uvm/uvm_fault.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_fault.c,v 1.122 2021/12/15 12:53:53 mpi Exp $	*/
+/*	$OpenBSD: uvm_fault.c,v 1.123 2021/12/17 14:18:15 mpi Exp $	*/
 /*	$NetBSD: uvm_fault.c,v 1.51 2000/08/06 00:22:53 thorpej Exp $	*/
 
 /*
@@ -1322,7 +1322,8 @@ uvm_fault_lower(struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
 		}
 
 		if (locked == FALSE) {
-			rw_exit(uobj->vmobjlock);
+			if (uobjpage != PGO_DONTCARE)
+				rw_exit(uobj->vmobjlock);
 			return ERESTART;
 		}