[PATCH] PR gdb/11092: Fix index overflow

[PATCH] PR gdb/11092: Fix index overflow

[Andreas Schwab]

The length parameter of c_printstr can be -1 meaning NUL terminated.
Compute real length before its first use as an index.

Andreas.

2010-05-17  Andreas Schwab  <schwab@redhat.com>

	PR gdb/11092
	* c-lang.c (c_printstr): Compute real length of NUL terminated
	string at first.

Index: c-lang.c
===================================================================
RCS file: /cvs/src/src/gdb/c-lang.c,v
retrieving revision 1.85
diff -a -u -p -a -u -p -r1.85 c-lang.c
--- c-lang.c	13 May 2010 23:53:32 -0000	1.85
+++ c-lang.c	17 May 2010 15:58:18 -0000
@@ -390,6 +390,19 @@ c_printstr (struct ui_file *stream, stru
   int finished = 0;
   int need_escape = 0;
 
+  if (length == -1)
+    {
+      unsigned long current_char = 1;
+
+      for (i = 0; current_char; ++i)
+	{
+	  QUIT;
+	  current_char = extract_unsigned_integer (string + i * width,
+						   width, byte_order);
+	}
+      length = i;
+    }
+
   /* If the string was not truncated due to `set print elements', and
      the last byte of it is a null, we don't print that, in traditional C
      style.  */
@@ -424,19 +437,6 @@ c_printstr (struct ui_file *stream, stru
       return;
     }
 
-  if (length == -1)
-    {
-      unsigned long current_char = 1;
-
-      for (i = 0; current_char; ++i)
-	{
-	  QUIT;
-	  current_char = extract_unsigned_integer (string + i * width,
-						   width, byte_order);
-	}
-      length = i;
-    }
-
   /* Arrange to iterate over the characters, in wchar_t form.  */
   iter = make_wchar_iterator (string, length * width, encoding, width);
   cleanup = make_cleanup_wchar_iterator (iter);

-- 
Andreas Schwab, schwab@redhat.com
GPG Key fingerprint = D4E8 DBE3 3813 BB5D FA84  5EC7 45C6 250E 6F00 984E
"And now for something completely different."

Re: [PATCH] PR gdb/11092: Fix index overflow

[Tom Tromey]

>>>>> "Andreas" == Andreas Schwab <schwab@redhat.com> writes:

Andreas> The length parameter of c_printstr can be -1 meaning NUL terminated.
Andreas> Compute real length before its first use as an index.

Andreas> 2010-05-17  Andreas Schwab  <schwab@redhat.com>
Andreas> 	PR gdb/11092
Andreas> 	* c-lang.c (c_printstr): Compute real length of NUL terminated
Andreas> 	string at first.

This is ok.  Thanks for fixing this.

Tom