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Date:      Mon, 10 Oct 2011 13:18:56 +0000 (UTC)
From:      Konstantin Belousov <kib@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-8@freebsd.org
Subject:   svn commit: r226207 - in stable/8/sys: amd64/amd64 i386/i386
Message-ID:  <201110101318.p9ADIu2R061923@svn.freebsd.org>
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Author: kib
Date: Mon Oct 10 13:18:55 2011
New Revision: 226207
URL: http://svn.freebsd.org/changeset/base/226207

Log:
  MFC r225943:
  Do not allow the kernel to access usermode pages without installed
  fault handler. Panic immediately in such situation, on i386 and amd64.

Modified:
  stable/8/sys/amd64/amd64/trap.c
  stable/8/sys/i386/i386/trap.c
Directory Properties:
  stable/8/sys/   (props changed)
  stable/8/sys/amd64/include/xen/   (props changed)
  stable/8/sys/cddl/contrib/opensolaris/   (props changed)
  stable/8/sys/contrib/dev/acpica/   (props changed)
  stable/8/sys/contrib/pf/   (props changed)

Modified: stable/8/sys/amd64/amd64/trap.c
==============================================================================
--- stable/8/sys/amd64/amd64/trap.c	Mon Oct 10 13:16:39 2011	(r226206)
+++ stable/8/sys/amd64/amd64/trap.c	Mon Oct 10 13:18:55 2011	(r226207)
@@ -678,6 +678,19 @@ trap_pfault(frame, usermode)
 			goto nogo;
 
 		map = &vm->vm_map;
+
+		/*
+		 * When accessing a usermode address, kernel must be
+		 * ready to accept the page fault, and provide a
+		 * handling routine.  Since accessing the address
+		 * without the handler is a bug, do not try to handle
+		 * it normally, and panic immediately.
+		 */
+		if (!usermode && (td->td_intr_nesting_level != 0 ||
+		    PCPU_GET(curpcb)->pcb_onfault == NULL)) {
+			trap_fatal(frame, eva);
+			return (-1);
+		}
 	}
 
 	/*

Modified: stable/8/sys/i386/i386/trap.c
==============================================================================
--- stable/8/sys/i386/i386/trap.c	Mon Oct 10 13:16:39 2011	(r226206)
+++ stable/8/sys/i386/i386/trap.c	Mon Oct 10 13:18:55 2011	(r226207)
@@ -835,6 +835,11 @@ trap_pfault(frame, usermode, eva)
 			goto nogo;
 
 		map = &vm->vm_map;
+		if (!usermode && (td->td_intr_nesting_level != 0 ||
+		    PCPU_GET(curpcb)->pcb_onfault == NULL)) {
+			trap_fatal(frame, eva);
+			return (-1);
+		}
 	}
 
 	/*

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