[src/trunk]: src/sys/kern We need VMCMDs for a binary and its interpreter, so...

[maxv <maxv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/76f65ce65e68
branches:  trunk
changeset: 326818:76f65ce65e68
user:      maxv <maxv%NetBSD.org@localhost>
date:      Wed Feb 19 15:23:20 2014 +0000

description:
We need VMCMDs for a binary and its interpreter, so make sure we have
at least one VMCMD. This also prevents the kernel from using an
uninitialized pointer as entry point for the execution.

>From me and Christos

ok christos@

diffstat:

 sys/kern/exec_elf.c  |  23 +++++++++++++++++++----
 sys/kern/kern_exec.c |   7 +++----
 2 files changed, 22 insertions(+), 8 deletions(-)

diffs (86 lines):

diff -r 4a9c8a0f51cb -r 76f65ce65e68 sys/kern/exec_elf.c
--- a/sys/kern/exec_elf.c       Wed Feb 19 13:30:45 2014 +0000
+++ b/sys/kern/exec_elf.c       Wed Feb 19 15:23:20 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: exec_elf.c,v 1.58 2014/02/16 17:46:36 maxv Exp $       */
+/*     $NetBSD: exec_elf.c,v 1.59 2014/02/19 15:23:20 maxv Exp $       */
 
 /*-
  * Copyright (c) 1994, 2000, 2005 The NetBSD Foundation, Inc.
@@ -57,7 +57,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(1, "$NetBSD: exec_elf.c,v 1.58 2014/02/16 17:46:36 maxv Exp $");
+__KERNEL_RCSID(1, "$NetBSD: exec_elf.c,v 1.59 2014/02/19 15:23:20 maxv Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_pax.h"
@@ -796,6 +796,14 @@
                        break;
                }
        }
+
+       if (epp->ep_vmcmds.evs_cmds == NULL) {
+               /* No VMCMD; there was no PT_LOAD section, or those
+                * sections were empty */
+               error = ENOEXEC;
+               goto bad;
+       }
+
        if (interp || (epp->ep_flags & EXEC_FORCEAUX) != 0) {
                ap = kmem_alloc(sizeof(*ap), KM_SLEEP);
                ap->arg_interp = (vaddr_t)NULL;
@@ -811,7 +819,7 @@
         * its interpreter
         */
        if (interp) {
-               int j = epp->ep_vmcmds.evs_used;
+               int nused = epp->ep_vmcmds.evs_used;
                u_long interp_offset = 0;
 
                if ((error = elf_load_file(l, epp, interp,
@@ -819,7 +827,14 @@
                        kmem_free(ap, sizeof(*ap));
                        goto bad;
                }
-               ap->arg_interp = epp->ep_vmcmds.evs_cmds[j].ev_addr;
+               if (epp->ep_vmcmds.evs_used == nused) {
+                       /* elf_load_file() has not set up any new VMCMD */
+                       kmem_free(ap, sizeof(*ap));
+                       error = ENOEXEC;
+                       goto bad;
+               }
+
+               ap->arg_interp = epp->ep_vmcmds.evs_cmds[nused].ev_addr;
                epp->ep_entry = ap->arg_interp + interp_offset;
                PNBUF_PUT(interp);
        } else
diff -r 4a9c8a0f51cb -r 76f65ce65e68 sys/kern/kern_exec.c
--- a/sys/kern/kern_exec.c      Wed Feb 19 13:30:45 2014 +0000
+++ b/sys/kern/kern_exec.c      Wed Feb 19 15:23:20 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_exec.c,v 1.376 2014/02/17 19:29:46 maxv Exp $     */
+/*     $NetBSD: kern_exec.c,v 1.377 2014/02/19 15:23:20 maxv Exp $     */
 
 /*-
  * Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -59,7 +59,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_exec.c,v 1.376 2014/02/17 19:29:46 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_exec.c,v 1.377 2014/02/19 15:23:20 maxv Exp $");
 
 #include "opt_exec.h"
 #include "opt_execfmt.h"
@@ -658,8 +658,7 @@
        data->ed_pack.ep_hdrvalid = 0;
        data->ed_pack.ep_emul_arg = NULL;
        data->ed_pack.ep_emul_arg_free = NULL;
-       data->ed_pack.ep_vmcmds.evs_cnt = 0;
-       data->ed_pack.ep_vmcmds.evs_used = 0;
+       memset(&data->ed_pack.ep_vmcmds, 0, sizeof(data->ed_pack.ep_vmcmds));
        data->ed_pack.ep_vap = &data->ed_attr;
        data->ed_pack.ep_flags = 0;
        MD_TOPDOWN_INIT(&data->ed_pack);