[src/trunk]: src/sys/arch/amd64/amd64 In cpu_mcontext32_validate, allow the r...

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

details:   https://anonhg.NetBSD.org/src/rev/93e223f8df53
branches:  trunk
changeset: 821453:93e223f8df53
user:      maxv <maxv%NetBSD.org@localhost>
date:      Mon Feb 06 16:34:37 2017 +0000

description:
In cpu_mcontext32_validate, allow the registers to have different locations
if the LDT is user-set.

I am intentionally not allowing this in check_sigcontext32, because I don't
think Wine uses it.

diffstat:

 sys/arch/amd64/amd64/netbsd32_machdep.c |  44 ++++++++++++++++++++------------
 1 files changed, 27 insertions(+), 17 deletions(-)

diffs (73 lines):

diff -r f4c2c01296a7 -r 93e223f8df53 sys/arch/amd64/amd64/netbsd32_machdep.c
--- a/sys/arch/amd64/amd64/netbsd32_machdep.c   Mon Feb 06 16:08:56 2017 +0000
+++ b/sys/arch/amd64/amd64/netbsd32_machdep.c   Mon Feb 06 16:34:37 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: netbsd32_machdep.c,v 1.100 2017/02/06 16:02:17 maxv Exp $      */
+/*     $NetBSD: netbsd32_machdep.c,v 1.101 2017/02/06 16:34:37 maxv Exp $      */
 
 /*
  * Copyright (c) 2001 Wasabi Systems, Inc.
@@ -36,7 +36,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: netbsd32_machdep.c,v 1.100 2017/02/06 16:02:17 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: netbsd32_machdep.c,v 1.101 2017/02/06 16:34:37 maxv Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_compat_netbsd.h"
@@ -1016,6 +1016,7 @@
 int
 cpu_mcontext32_validate(struct lwp *l, const mcontext32_t *mcp)
 {
+       struct pmap *pmap = l->l_proc->p_vmspace->vm_map.pmap;
        const __greg32_t *gr;
        struct trapframe *tf;
        struct pcb *pcb;
@@ -1024,22 +1025,31 @@
        tf = l->l_md.md_regs;
        pcb = lwp_getpcb(l);
 
-       if (((gr[_REG32_EFL] ^ tf->tf_rflags) & PSL_USERSTATIC) != 0 ||
-           !VALID_USER_CSEL32(gr[_REG32_CS]))
-               return EINVAL;
-       if (gr[_REG32_FS] != 0 && !VALID_USER_DSEL32(gr[_REG32_FS]) &&
-           !(VALID_USER_FSEL32(gr[_REG32_FS]) && pcb->pcb_fs != 0))
+       if (((gr[_REG32_EFL] ^ tf->tf_rflags) & PSL_USERSTATIC) != 0)
                return EINVAL;
-       if (gr[_REG32_GS] != 0 && !VALID_USER_DSEL32(gr[_REG32_GS]) &&
-           !(VALID_USER_GSEL32(gr[_REG32_GS]) && pcb->pcb_gs != 0))
-               return EINVAL;
-       if (gr[_REG32_ES] != 0 && !VALID_USER_DSEL32(gr[_REG32_ES]))
-               return EINVAL;
-       if (!VALID_USER_DSEL32(gr[_REG32_DS]) ||
-           !VALID_USER_DSEL32(gr[_REG32_SS]))
-               return EINVAL;
-       if (gr[_REG32_EIP] >= VM_MAXUSER_ADDRESS32)
-               return EINVAL;
+
+       if (__predict_false(pmap->pm_ldt != NULL)) {
+               /* Only when the LDT is user-set (with USER_LDT) */
+               if (!USERMODE(gr[_REG32_CS], gr[_REG32_EFL]))
+                       return EINVAL;
+       } else {
+               if (!VALID_USER_CSEL32(gr[_REG32_CS]))
+                       return EINVAL;
+               if (gr[_REG32_FS] != 0 && !VALID_USER_DSEL32(gr[_REG32_FS]) &&
+                   !(VALID_USER_FSEL32(gr[_REG32_FS]) && pcb->pcb_fs != 0))
+                       return EINVAL;
+               if (gr[_REG32_GS] != 0 && !VALID_USER_DSEL32(gr[_REG32_GS]) &&
+                   !(VALID_USER_GSEL32(gr[_REG32_GS]) && pcb->pcb_gs != 0))
+                       return EINVAL;
+               if (gr[_REG32_ES] != 0 && !VALID_USER_DSEL32(gr[_REG32_ES]))
+                       return EINVAL;
+               if (!VALID_USER_DSEL32(gr[_REG32_DS]) ||
+                   !VALID_USER_DSEL32(gr[_REG32_SS]))
+                       return EINVAL;
+               if (gr[_REG32_EIP] >= VM_MAXUSER_ADDRESS32)
+                       return EINVAL;
+       }
+
        return 0;
 }