git: 5c50e900ad77 - main - vm_fault: Shoot down shared mappings in vm_fault_copy_entry()

The branch main has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=5c50e900ad779fccbf0a230bfb6a68a3e93ccf60

commit 5c50e900ad779fccbf0a230bfb6a68a3e93ccf60
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2022-07-25 20:53:21 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2022-08-09 19:44:45 +0000

    vm_fault: Shoot down shared mappings in vm_fault_copy_entry()
    
    As in vm_fault_cow(), it's possible, albeit rare, for multiple vm_maps
    to share a shadow object.  When copying a page from a backing object
    into the shadow, all mappings of the source page must therefore be
    removed.  Otherwise, future operations on the object tree may detect
    that the source page is fully shadowed and thus can be freed.
    
    Approved by:    so
    Security:       FreeBSD-SA-22:11.vm
    Reviewed by:    alc, kib
    Sponsored by:   The FreeBSD Foundation
    Differential Revision:  https://reviews.freebsd.org/D35635
---
 sys/vm/vm_fault.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/sys/vm/vm_fault.c b/sys/vm/vm_fault.c
index 0433b6dd3d7e..8f30c5b93828 100644
--- a/sys/vm/vm_fault.c
+++ b/sys/vm/vm_fault.c
@@ -2107,6 +2107,13 @@ again:
 				VM_OBJECT_WLOCK(dst_object);
 				goto again;
 			}
+
+			/*
+			 * See the comment in vm_fault_cow().
+			 */
+			if (src_object == dst_object &&
+			    (object->flags & OBJ_ONEMAPPING) == 0)
+				pmap_remove_all(src_m);
 			pmap_copy_page(src_m, dst_m);
 
 			/*