From 11816c5585352dffa7bdfcbe73dd0f768d3d5767 Mon Sep 17 00:00:00 2001 From: kn Date: Mon, 14 Feb 2022 21:11:02 +0000 Subject: [PATCH] Unwire with map lock held This is an updated version of uvm_map.c r1.283 "Unwire with map lock held". The previous version introduced a use-after-free by not unlocking vm_map locks in uvm_map_teardown(), resulting in dangling references on the reaper's lock list (thanks visa!). Lock and unlock the map in around uvm_map_teardown() instead. This code path holds the last reference, hence the lock isn't strictly needed except for satisfying upcoming locking assertions. Tested on amd64, arm64, i386, macppc, octeon, sparc64. This time also with WITNESS enabled (except on sparc64 which builds but does not boot with WITNESS; this is a known issue). OK mpi visa --- sys/uvm/uvm_map.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/sys/uvm/uvm_map.c b/sys/uvm/uvm_map.c index 9263c4d8ab5..6cb8b05acea 100644 --- a/sys/uvm/uvm_map.c +++ b/sys/uvm/uvm_map.c @@ -1,4 +1,4 @@ -/* $OpenBSD: uvm_map.c,v 1.286 2022/02/11 12:06:48 kn Exp $ */ +/* $OpenBSD: uvm_map.c,v 1.287 2022/02/14 21:11:02 kn Exp $ */ /* $NetBSD: uvm_map.c,v 1.86 2000/11/27 08:40:03 chs Exp $ */ /* @@ -3681,7 +3681,9 @@ uvmspace_free(struct vmspace *vm) shmexit(vm); #endif + vm_map_lock(&vm->vm_map); uvm_map_teardown(&vm->vm_map); + vm_map_unlock(&vm->vm_map); pool_put(&uvm_vmspace_pool, vm); } } -- 2.20.1