Bug 1090598: Once we have hit the ah_crap_handler, allow any process (such as gdb) to ptrace us. r=froydnj

Author: khuey

toolkit/xre/nsSigHandlers.cpp

@@ -26,6 +26,7 @@
 #include <sys/resource.h>
 #include <unistd.h>
 #include <stdlib.h> // atoi
+#include <sys/prctl.h>
 #ifndef ANDROID // no Android impl
 #  include <ucontext.h>
 #endif
@@ -44,6 +45,13 @@ static unsigned int _gdb_sleep_duration = 300;
 #define CRAWL_STACK_ON_SIGSEGV
 #endif
 
+#ifndef PR_SET_PTRACER
+#define PR_SET_PTRACER 0x59616d61
+#endif
+#ifndef PR_SET_PTRACER_ANY
+#define PR_SET_PTRACER_ANY ((unsigned long)-1)
+#endif
+
 #if defined(CRAWL_STACK_ON_SIGSEGV)
 
 #include <unistd.h>
@@ -87,6 +95,9 @@ ah_crap_handler(int signum)
          _progname,
          getpid());
 
+  // Allow us to be ptraced by gdb on Linux with Yama restrictions enabled.
+  prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY);
+
   sleep(_gdb_sleep_duration);
 
   printf("Done sleeping...\n");