svn commit: r243408 - stable/9/sys/dev/md

[Konstantin Belousov]

Author: kib
Date: Thu Nov 22 16:20:08 2012
New Revision: 243408
URL: http://svnweb.freebsd.org/changeset/base/243408

Log:
  MFC r242744:
  Zero the newly allocated md(4) swap-backed page to prevent random
  kernel memory leakage to userspace.

Modified:
  stable/9/sys/dev/md/md.c
Directory Properties:
  stable/9/sys/   (props changed)
  stable/9/sys/dev/   (props changed)

Modified: stable/9/sys/dev/md/md.c
==============================================================================
--- stable/9/sys/dev/md/md.c	Thu Nov 22 16:14:41 2012	(r243407)
+++ stable/9/sys/dev/md/md.c	Thu Nov 22 16:20:08 2012	(r243408)
@@ -677,6 +677,15 @@ mdstart_swap(struct md_s *sc, struct bio
 				sched_unpin();
 				vm_page_wakeup(m);
 				break;
+			} else if (rv == VM_PAGER_FAIL) {
+				/*
+				 * Pager does not have the page.  Zero
+				 * the allocated page, and mark it as
+				 * valid. Do not set dirty, the page
+				 * can be recreated if thrown out.
+				 */
+				bzero((void *)sf_buf_kva(sf), PAGE_SIZE);
+				m->valid = VM_PAGE_BITS_ALL;
 			}
 			bcopy((void *)(sf_buf_kva(sf) + offs), p, len);
 			cpu_flush_dcache(p, len);