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

4 files changed, 39 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index 0eb779d91f..da0b76943a 100644
--- a/ChangeLog
+++ b/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
diff --git a/NEWS b/NEWS
index 1f98e58da2..b4df84900f 100644
--- a/NEWS
+++ b/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
diff --git a/posix/wordexp-test.c b/posix/wordexp-test.c
index 8a312e0bcd..137044e95f 100644
--- a/posix/wordexp-test.c
+++ b/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;
 }
 
diff --git a/posix/wordexp.c b/posix/wordexp.c
index e3d8d6bd0d..1c144014b3 100644
--- a/posix/wordexp.c
+++ b/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;