From: mvs <mvs@openbsd.org>
Date: Tue, 15 Nov 2022 17:16:44 +0000 (+0000)
Subject: Take `vmobjlock' around uao_grow() and uao_shrink() calls to fix tmpfs
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=af1a00402c380b79c08745e93c887198201e9024;p=openbsd

Take `vmobjlock' around uao_grow() and uao_shrink() calls to fix tmpfs
panics [1].

1. https://marc.info/?l=openbsd-bugs&m=165012301707403&w=2

from Leo Larnack <leo at pseven.xyz>

ok kn@ mpi@
---

diff --git a/sys/tmpfs/tmpfs_subr.c b/sys/tmpfs/tmpfs_subr.c
index 0666f04ee9a..04d3e900fe6 100644
--- a/sys/tmpfs/tmpfs_subr.c
+++ b/sys/tmpfs/tmpfs_subr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: tmpfs_subr.c,v 1.25 2021/10/24 17:20:06 patrick Exp $	*/
+/*	$OpenBSD: tmpfs_subr.c,v 1.26 2022/11/15 17:16:44 mvs Exp $	*/
 /*	$NetBSD: tmpfs_subr.c,v 1.79 2012/03/13 18:40:50 elad Exp $	*/
 
 /*
@@ -884,7 +884,10 @@ tmpfs_reg_resize(struct vnode *vp, off_t newsize)
 		bytes = (newpages - oldpages) << PAGE_SHIFT;
 		if (tmpfs_mem_incr(tmp, bytes) == 0)
 			return ENOSPC;
-		if (uao_grow(uobj, newpages) != 0) {
+		rw_enter(uobj->vmobjlock, RW_WRITE);
+		error = uao_grow(uobj, newpages);
+		rw_exit(uobj->vmobjlock);
+		if (error) {
 			tmpfs_mem_decr(tmp, bytes);
 			return ENOSPC;
 		}
@@ -901,8 +904,10 @@ tmpfs_reg_resize(struct vnode *vp, off_t newsize)
 	if (newpages < oldpages) {
 		if (tmpfs_uio_cached(node))
 			tmpfs_uio_uncache(node);
+		rw_enter(uobj->vmobjlock, RW_WRITE);
 		if (uao_shrink(uobj, newpages))
 			panic("shrink failed");
+		rw_exit(uobj->vmobjlock);
 		/* Decrease the used-memory counter. */
 		tmpfs_mem_decr(tmp, (oldpages - newpages) << PAGE_SHIFT);
 	}