Fix BZ #18043: buffer-overflow (read past the end) in wordexp/parse_dollars/parse_param

ChangeLog

@@ -1,3 +1,9 @@
+2015-03-06  Paul Pluzhnikov  <ppluzhnikov@google.com>
+
+	[BZ #18043]
+	* posix/wordexp.c (parse_param): Fix buffer overflow.
+	* posix/wordexp-test.c (do_bz18043): Add test case.
+
 2015-03-06  Vincent Bernat  <vincent@bernat.im>
 
 	* time/tst-strptime2.c (do_test): Ensure failing tests are

NEWS

@@ -13,7 +13,7 @@ Version 2.22
   16560, 16783, 17269, 17523, 17569, 17588, 17631, 17711, 17776, 17779,
   17792, 17836, 17912, 17916, 17932, 17944, 17949, 17964, 17965, 17967,
   17969, 17978, 17987, 17991, 17996, 17998, 17999, 18019, 18020, 18029,
-  18030, 18032, 18036, 18038, 18039, 18046, 18047.
+  18030, 18032, 18036, 18038, 18039, 18043, 18046, 18047.
 
 * Character encoding and ctype tables were updated to Unicode 7.0.0, using
   new generator scripts contributed by Pravin Satpute and Mike FABIAN (Red

posix/wordexp-test.c

@@ -17,6 +17,7 @@
 
 #include <sys/stat.h>
 #include <sys/types.h>
+#include <sys/mman.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <pwd.h>
@@ -249,6 +250,33 @@ command_line_test (const char *words)
     printf ("we_wordv[%d] = \"%s\"\n", i, we.we_wordv[i]);
 }
 
+static int
+do_bz18043 (void)
+{
+  const int pagesize = getpagesize ();
+  char *start = mmap (0, 2 * pagesize, PROT_READ|PROT_WRITE,
+		      MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+
+  if (start == MAP_FAILED)
+    return 1;
+
+  if (mprotect (start + pagesize, pagesize, PROT_NONE))
+    return 2;
+
+  const char word[] = "${";
+  char *word_start = start + pagesize - sizeof (word);
+  memcpy (word_start, word, sizeof (word));
+
+  wordexp_t w;
+  if (wordexp (word_start, &w, 0) != WRDE_SYNTAX)
+    return 3;
+
+  if (munmap (start, 2 * pagesize) != 0)
+    return 4;
+
+  return 0;
+}
+
 int
 main (int argc, char *argv[])
 {
@@ -370,6 +398,9 @@ main (int argc, char *argv[])
 
   printf ("tests failed: %d\n", fail);
 
+  if (do_bz18043 ())
+    ++fail;
+
   return fail != 0;
 }
 

posix/wordexp.c

@@ -1299,7 +1299,7 @@ parse_param (char **word, size_t *word_length, size_t *max_length,
 	}
       while (isdigit(words[++*offset]));
     }
-  else if (strchr ("*@$", words[*offset]) != NULL)
+  else if (words[*offset] != '\0' && strchr ("*@$", words[*offset]) != NULL)
     {
       /* Special parameter. */
       special = 1;