[src/trunk]: src/sys/kern Turn KASSERTS that check alignment which are user t...

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

details:   https://anonhg.NetBSD.org/src/rev/e1da0a729cfe
branches:  trunk
changeset: 321487:e1da0a729cfe
user:      christos <christos%NetBSD.org@localhost>
date:      Sun Mar 18 02:16:21 2018 +0000

description:
Turn KASSERTS that check alignment which are user triggerable into errors.
>From alnsn

diffstat:

 sys/kern/exec_elf.c |  40 +++++++++++++++++++++++++++-------------
 1 files changed, 27 insertions(+), 13 deletions(-)

diffs (122 lines):

diff -r 0bb6efd96f24 -r e1da0a729cfe sys/kern/exec_elf.c
--- a/sys/kern/exec_elf.c       Sun Mar 18 00:51:45 2018 +0000
+++ b/sys/kern/exec_elf.c       Sun Mar 18 02:16:21 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: exec_elf.c,v 1.94 2018/03/17 00:30:50 christos Exp $   */
+/*     $NetBSD: exec_elf.c,v 1.95 2018/03/18 02:16:21 christos Exp $   */
 
 /*-
  * Copyright (c) 1994, 2000, 2005, 2015 The NetBSD Foundation, Inc.
@@ -57,7 +57,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(1, "$NetBSD: exec_elf.c,v 1.94 2018/03/17 00:30:50 christos Exp $");
+__KERNEL_RCSID(1, "$NetBSD: exec_elf.c,v 1.95 2018/03/18 02:16:21 christos Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_pax.h"
@@ -101,7 +101,7 @@
 static int
 elf_load_interp(struct lwp *, struct exec_package *, char *,
     struct exec_vmcmd_set *, u_long *, Elf_Addr *);
-static void
+static int
 elf_load_psection(struct exec_vmcmd_set *, struct vnode *, const Elf_Phdr *,
     Elf_Addr *, u_long *, int);
 
@@ -123,7 +123,7 @@
 #define        ELF_ROUND(a, b)         (((a) + (b) - 1) & ~((b) - 1))
 #define        ELF_TRUNC(a, b)         ((a) & ~((b) - 1))
 
-static void
+static int
 elf_placedynexec(struct exec_package *epp, Elf_Ehdr *eh, Elf_Phdr *ph)
 {
        Elf_Addr align, offset;
@@ -136,12 +136,17 @@
        offset = (Elf_Addr)pax_aslr_exec_offset(epp, align);
        if (offset < epp->ep_vm_minaddr)
                offset = roundup(epp->ep_vm_minaddr, align);
-       KASSERT((offset & (align - 1)) == 0);
+       if ((offset & (align - 1)) != 0) {
+               DPRINTF("bad offset=%#jx align=%#jx",
+                   (uintmax_t)offset, (uintmax_t)align);
+               return EINVAL;
+       }
 
        for (i = 0; i < eh->e_phnum; i++)
                ph[i].p_vaddr += offset;
        epp->ep_entryoffset = offset;
        eh->e_entry += offset;
+       return 0;
 }
 
 /*
@@ -305,7 +310,7 @@
  *
  * Load a psection at the appropriate address
  */
-static void
+static int
 elf_load_psection(struct exec_vmcmd_set *vcset, struct vnode *vp,
     const Elf_Phdr *ph, Elf_Addr *addr, u_long *size, int flags)
 {
@@ -324,7 +329,12 @@
                 * Make sure we are virtually aligned as we are supposed to be.
                 */
                diff = ph->p_vaddr - ELF_TRUNC(ph->p_vaddr, ph->p_align);
-               KASSERT(*addr - diff == ELF_TRUNC(*addr, ph->p_align));
+               if (*addr - diff != ELF_TRUNC(*addr, ph->p_align)) {
+                       DPRINTF("bad alignment %#jx != %#jx\n",
+                           (uintptr_t)(*addr - diff),
+                           (uintptr_t)ELF_TRUNC(*addr, ph->p_align));
+                       return EINVAL;
+               }
                /*
                 * But make sure to not map any pages before the start of the
                 * psection by limiting the difference to within a page.
@@ -383,6 +393,7 @@
                    0, vmprot, flags & VMCMD_RELATIVE);
                *size = msize;
        }
+       return 0;
 }
 
 /*
@@ -580,8 +591,9 @@
                                flags = VMCMD_RELATIVE;
                        }
                        last_ph = &ph[i];
-                       elf_load_psection(vcset, vp, &ph[i], &addr,
-                           &size, flags);
+                       if ((error = elf_load_psection(vcset, vp, &ph[i], &addr,
+                           &size, flags)) != 0)
+                               goto bad;
                        /*
                         * If entry is within this psection then this
                         * must contain the .text section.  *entryoff is
@@ -719,8 +731,8 @@
                pos = (Elf_Addr)startp;
        }
 
-       if (is_dyn)
-               elf_placedynexec(epp, eh, ph);
+       if (is_dyn && (error = elf_placedynexec(epp, eh, ph)) != 0)
+               goto bad;
 
        /*
         * Load all the necessary sections
@@ -731,8 +743,10 @@
 
                switch (ph[i].p_type) {
                case PT_LOAD:
-                       elf_load_psection(&epp->ep_vmcmds, epp->ep_vp,
-                           &ph[i], &addr, &size, VMCMD_FIXED);
+                       if ((error = elf_load_psection(&epp->ep_vmcmds,
+                           epp->ep_vp, &ph[i], &addr, &size, VMCMD_FIXED))
+                           != 0)
+                               goto bad;
 
                        /*
                         * Consider this as text segment, if it is executable.