i#6541 privlib: Add try/except around private library init/fini

Wraps private library init/fini calls in a try/except on Linux (as is
already done on Windows) and reports a crash as a SYSLOG_ERROR
pointing at the library's name.  This is much better than a weird
assert or mysterious secondary crash later.

Adds a check for shared_data==NULL in check_thread_in_last_vmwarea()
to avoid a crash seen there.

Issue: #6541

core/unix/loader.c

@@ -1,5 +1,5 @@
 /* *******************************************************************************
- * Copyright (c) 2011-2023 Google, Inc.  All rights reserved.
+ * Copyright (c) 2011-2024 Google, Inc.  All rights reserved.
  * Copyright (c) 2011 Massachusetts Institute of Technology  All rights reserved.
  * *******************************************************************************/
 
@@ -157,7 +157,7 @@ static privmod_t *
 privload_locate_and_load(const char *impname, privmod_t *dependent, bool reachable);
 
 static void
-privload_call_lib_func(fp_t func);
+privload_call_lib_func(dcontext_t *dcontext, privmod_t *privmod, fp_t func);
 
 static void
 privload_relocate_mod(privmod_t *mod);
@@ -618,15 +618,15 @@ privload_call_entry(dcontext_t *dcontext, privmod_t *privmod, uint reason)
         if (opd->init != NULL) {
             LOG(GLOBAL, LOG_LOADER, 4, "%s: calling %s init func " PFX "\n", __FUNCTION__,
                 privmod->name, opd->init);
-            privload_call_lib_func(opd->init);
+            privload_call_lib_func(dcontext, privmod, opd->init);
         }
         if (opd->init_array != NULL) {
             uint i;
             for (i = 0; i < opd->init_arraysz / sizeof(opd->init_array[i]); i++) {
                 if (opd->init_array[i] != NULL) { /* be paranoid */
                     LOG(GLOBAL, LOG_LOADER, 4, "%s: calling %s init array func " PFX "\n",
                         __FUNCTION__, privmod->name, opd->init_array[i]);
-                    privload_call_lib_func(opd->init_array[i]);
+                    privload_call_lib_func(dcontext, privmod, opd->init_array[i]);
                 }
             }
         }
@@ -648,15 +648,15 @@ privload_call_entry(dcontext_t *dcontext, privmod_t *privmod, uint reason)
         if (opd->fini != NULL) {
             LOG(GLOBAL, LOG_LOADER, 4, "%s: calling %s fini func " PFX "\n", __FUNCTION__,
                 privmod->name, opd->fini);
-            privload_call_lib_func(opd->fini);
+            privload_call_lib_func(dcontext, privmod, opd->fini);
         }
         if (opd->fini_array != NULL) {
             uint i;
             for (i = 0; i < opd->fini_arraysz / sizeof(opd->fini_array[0]); i++) {
                 if (opd->fini_array[i] != NULL) { /* be paranoid */
                     LOG(GLOBAL, LOG_LOADER, 4, "%s: calling %s fini array func " PFX "\n",
                         __FUNCTION__, privmod->name, opd->fini_array[i]);
-                    privload_call_lib_func(opd->fini_array[i]);
+                    privload_call_lib_func(dcontext, privmod, opd->fini_array[i]);
                 }
             }
         }
@@ -1064,7 +1064,7 @@ get_private_library_address(app_pc modbase, const char *name)
 }
 
 static void
-privload_call_lib_func(fp_t func)
+privload_call_lib_func(dcontext_t *dcontext, privmod_t *privmod, fp_t func)
 {
     char dummy_str[] = "dummy";
     char *dummy_argv[2];
@@ -1076,7 +1076,12 @@ privload_call_lib_func(fp_t func)
      */
     dummy_argv[0] = dummy_str;
     dummy_argv[1] = NULL;
-    func(1, dummy_argv, our_environ);
+    TRY_EXCEPT_ALLOW_NO_DCONTEXT(
+        dcontext, { func(1, dummy_argv, our_environ); },
+        { /* EXCEPT */
+          SYSLOG_INTERNAL_ERROR("Private library %s init/fini func " PFX " crashed",
+                                privmod->name, func);
+        });
 }
 
 bool

core/vmareas.c

@@ -1,5 +1,5 @@
 /* **********************************************************
- * Copyright (c) 2010-2023 Google, Inc.  All rights reserved.
+ * Copyright (c) 2010-2024 Google, Inc.  All rights reserved.
  * Copyright (c) 2002-2010 VMware, Inc.  All rights reserved.
  * **********************************************************/
 
@@ -8385,7 +8385,7 @@ check_in_last_thread_vm_area(dcontext_t *dcontext, app_pc pc)
                    data->last_area->start <= pc);
     }
     /* last decoded app pc may be in last shared area instead */
-    if (!in_last && DYNAMO_OPTION(shared_bbs)) {
+    if (!in_last && DYNAMO_OPTION(shared_bbs) && shared_data != NULL) {
         /* We avoid the high-ranked shared_vm_areas lock which can easily cause
          * rank order violations (i#3346).  We're trying to catch the scenario
          * where a shared bb is being built and we fault decoding it.  There,