remote: Map invalid signal numbers to GDB_SIGNAL_UNKNOWN.

I realized that remote.c is not validating input here.  Currently, if
a remote stub sends in an invalid signal number (or put another way,
if a future stub sends a new signal an old GDB doesn't know about),
GDB will do out of bounds accesses in the
signal_pass/signal_stop/signal_program arrays.  It'll probably be a
long while before we add another signal number (and buggy stubs should
just be fixed), but can't hurt to be defensive.

Tested on x86_64 Fedora 17, native gdbserver.

gdb/
2013-10-22  Pedro Alves  <palves@redhat.com>

	* remote.c (remote_parse_stop_reply) <'T'/'S'/'X' replies>: Map
	invalid signal numbers to GDB_SIGNAL_UNKNOWN.

diff --git a/gdb/remote.c b/gdb/remote.c
index a2e8a01b2f1d70b0a5c5432378afbac9eada52f7..7d8a4deb77a937f3784cdde6d19dac4de104a71c 100644 (file)
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -5720,9 +5720,16 @@ Packet: '%s'\n"),
 
       /* fall through */
     case 'S':          /* Old style status, just signal only.  */
-      event->ws.kind = TARGET_WAITKIND_STOPPED;
-      event->ws.value.sig = (enum gdb_signal)
-       (((fromhex (buf[1])) << 4) + (fromhex (buf[2])));
+      {
+       int sig;
+
+       event->ws.kind = TARGET_WAITKIND_STOPPED;
+       sig = (fromhex (buf[1]) << 4) + fromhex (buf[2]);
+       if (GDB_SIGNAL_FIRST <= sig && sig < GDB_SIGNAL_LAST)
+         event->ws.value.sig = (enum gdb_signal) sig;
+       else
+         event->ws.value.sig = GDB_SIGNAL_UNKNOWN;
+      }
       break;
     case 'W':          /* Target exited.  */
     case 'X':
@@ -5746,7 +5753,10 @@ Packet: '%s'\n"),
          {
            /* The remote process exited with a signal.  */
            event->ws.kind = TARGET_WAITKIND_SIGNALLED;
-           event->ws.value.sig = (enum gdb_signal) value;
+           if (GDB_SIGNAL_FIRST <= value && value < GDB_SIGNAL_LAST)
+             event->ws.value.sig = (enum gdb_signal) value;
+           else
+             event->ws.value.sig = GDB_SIGNAL_UNKNOWN;
          }
 
        /* If no process is specified, assume inferior_ptid.  */