[src/netbsd-6]: src/lib/libpthread Apply patch (requested by riastradh in tic...

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

details:   https://anonhg.NetBSD.org/src/rev/567dabf12e71
branches:  netbsd-6
changeset: 775557:567dabf12e71
user:      jdc <jdc%NetBSD.org@localhost>
date:      Mon Dec 03 19:07:26 2012 +0000

description:
Apply patch (requested by riastradh in ticket #735) to fix the unchecked
assumption that sizeof(struct __pthread_st) <= pagesize, as observed in
PR 47271.

diffstat:

 lib/libpthread/pthread.c |  24 +++++++++++++++++-------
 1 files changed, 17 insertions(+), 7 deletions(-)

diffs (56 lines):

diff -r b931823c8768 -r 567dabf12e71 lib/libpthread/pthread.c
--- a/lib/libpthread/pthread.c  Mon Dec 03 04:54:49 2012 +0000
+++ b/lib/libpthread/pthread.c  Mon Dec 03 19:07:26 2012 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: pthread.c,v 1.125.4.1 2012/05/07 03:12:33 riz Exp $    */
+/*     $NetBSD: pthread.c,v 1.125.4.2 2012/12/03 19:07:26 jdc Exp $    */
 
 /*-
  * Copyright (c) 2001, 2002, 2003, 2006, 2007, 2008 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: pthread.c,v 1.125.4.1 2012/05/07 03:12:33 riz Exp $");
+__RCSID("$NetBSD: pthread.c,v 1.125.4.2 2012/12/03 19:07:26 jdc Exp $");
 
 #define        __EXPOSE_STACK  1
 
@@ -1274,22 +1274,32 @@
 {
        pthread_t t;
        void *redaddr;
-       size_t pagesize;
+       size_t pagesize, bytes_needed;
        int ret;
 
        t = base;
        pagesize = (size_t)sysconf(_SC_PAGESIZE);
+       bytes_needed = roundup(sizeof(*t), pagesize);
+
+       if (pagesize >= size)
+               return ENOMEM;
+       if (bytes_needed >= (size - pagesize))
+               return ENOMEM;
 
        /*
         * Put a pointer to the pthread in the bottom (but
          * redzone-protected section) of the stack. 
+        *
+        * XXX If the stack grows up, the pthread is *not*
+        * protected by the redzone.
         */
-       redaddr = STACK_SHRINK(STACK_MAX(base, size), pagesize);
-       t->pt_stack.ss_size = size - 2 * pagesize;
+       t->pt_stack.ss_size = size - bytes_needed - pagesize;
 #ifdef __MACHINE_STACK_GROWS_UP
-       t->pt_stack.ss_sp = (char *)(void *)base + pagesize;
+       redaddr = STACK_SHRINK(STACK_MAX(base, size), pagesize);
+       t->pt_stack.ss_sp = (char *)(void *)base + bytes_needed;
 #else
-       t->pt_stack.ss_sp = (char *)(void *)base + 2 * pagesize;
+       redaddr = STACK_SHRINK(STACK_MAX(base, size), bytes_needed);
+       t->pt_stack.ss_sp = (char *)(void *)base + bytes_needed + pagesize;
 #endif
        /* Protect the next-to-bottom stack page as a red zone. */
        ret = mprotect(redaddr, pagesize, PROT_NONE);