From 045c55b2a296988c16a4c1b90f3d8b7e8b78752b Mon Sep 17 00:00:00 2001
From: Lassi Tuura <lat@cern.ch>
Date: Sat, 24 Apr 2010 19:24:49 -0700
Subject: [PATCH] Be conservative in all pointer derefrences by default.

Since most people can't completely control their compile or runtime
environment, it becomes hard to ensure that unwind data is perfect.
---
 configure.in             | 6 ++++++
 src/x86_64/Ginit_local.c | 4 ++++
 2 files changed, 10 insertions(+)

diff --git a/configure.in b/configure.in
index fcc88137..e42445b2 100644
--- a/configure.in
+++ b/configure.in
@@ -169,6 +169,12 @@ if test x$enable_block_signals = xyes; then
   AC_DEFINE([CONFIG_BLOCK_SIGNALS], [], [Block signals before mutex operations])
 fi
 
+AC_ARG_ENABLE(conservative_checks,
+[ --enable-conservative-checks Validate all memory addresses before use],
+[enable_conservative_checks=$enableval], [enable_conservative_checks=yes])
+if test x$enable_conservative_checks = xyes; then
+  CPPFLAGS="${CPPFLAGS} -DCONSERVATIVE_CHECKS"
+fi
 
 LIBUNWIND___THREAD
 
diff --git a/src/x86_64/Ginit_local.c b/src/x86_64/Ginit_local.c
index 70bef3e1..18b3d989 100644
--- a/src/x86_64/Ginit_local.c
+++ b/src/x86_64/Ginit_local.c
@@ -51,7 +51,11 @@ unw_init_local (unw_cursor_t *cursor, ucontext_t *uc)
   c->dwarf.as = unw_local_addr_space;
   c->dwarf.as_arg = c;
   c->uc = uc;
+#if CONSERVATIVE_CHECKS
+  c->validate = 1;
+#else
   c->validate = 0;
+#endif
   return common_init (c, 1);
 }