Fix where out of range data to strftime() causes a segfault (BZ18985, CVE-2015-8776)

diff --git a/README.google b/README.google
index 3e1e215304cb13f1af2b60be6046dcff570ba14e..a8153886b994de5c3c50517bb62c3ee22ab57a41 100644 (file)
--- a/README.google
+++ b/README.google
@@ -629,3 +629,9 @@ posix/fnmatch_loop.c
 nss/tst-nss-getpwent.c
   Work around b/34251679 by restricting to nss_files module
   (stanshebs, google-local)
+
+time/strftime_l.c
+time/tst-strftime.c
+  Fix where out of range data to strftime() causes a segfault (BZ18985, CVE-2015-8776)
+  https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=d36c75fc0d44deec29635dd239b0fbd206ca49b7
+  (stanshebs, backport)

diff --git a/time/strftime_l.c b/time/strftime_l.c
index dfb7b4c483b9f4c5b0b88d9f7a3e11a0b78c6ef9..29c7cdd556c083b41339855daaa748f4e3ccc8c7 100644 (file)
--- a/time/strftime_l.c
+++ b/time/strftime_l.c
@@ -509,13 +509,17 @@ __strftime_internal (s, maxsize, format, tp, tzset_called ut_argument
      only a few elements.  Dereference the pointers only if the format
      requires this.  Then it is ok to fail if the pointers are invalid.  */
 # define a_wkday \
-  ((const CHAR_T *) _NL_CURRENT (LC_TIME, NLW(ABDAY_1) + tp->tm_wday))
+  ((const CHAR_T *) (tp->tm_wday < 0 || tp->tm_wday > 6                             \
+                    ? "?" : _NL_CURRENT (LC_TIME, NLW(ABDAY_1) + tp->tm_wday)))
 # define f_wkday \
-  ((const CHAR_T *) _NL_CURRENT (LC_TIME, NLW(DAY_1) + tp->tm_wday))
+  ((const CHAR_T *) (tp->tm_wday < 0 || tp->tm_wday > 6                             \
+                    ? "?" : _NL_CURRENT (LC_TIME, NLW(DAY_1) + tp->tm_wday)))
 # define a_month \
-  ((const CHAR_T *) _NL_CURRENT (LC_TIME, NLW(ABMON_1) + tp->tm_mon))
+  ((const CHAR_T *) (tp->tm_mon < 0 || tp->tm_mon > 11                      \
+                    ? "?" : _NL_CURRENT (LC_TIME, NLW(ABMON_1) + tp->tm_mon)))
 # define f_month \
-  ((const CHAR_T *) _NL_CURRENT (LC_TIME, NLW(MON_1) + tp->tm_mon))
+  ((const CHAR_T *) (tp->tm_mon < 0 || tp->tm_mon > 11                      \
+                    ? "?" : _NL_CURRENT (LC_TIME, NLW(MON_1) + tp->tm_mon)))
 # define ampm \
   ((const CHAR_T *) _NL_CURRENT (LC_TIME, tp->tm_hour > 11                   \
                                 ? NLW(PM_STR) : NLW(AM_STR)))
@@ -525,8 +529,10 @@ __strftime_internal (s, maxsize, format, tp, tzset_called ut_argument
 # define ap_len STRLEN (ampm)
 #else
 # if !HAVE_STRFTIME
-#  define f_wkday (weekday_name[tp->tm_wday])
-#  define f_month (month_name[tp->tm_mon])
+#  define f_wkday (tp->tm_wday < 0 || tp->tm_wday > 6  \
+                  ? "?" : weekday_name[tp->tm_wday])
+#  define f_month (tp->tm_mon < 0 || tp->tm_mon > 11   \
+                  ? "?" : month_name[tp->tm_mon])
 #  define a_wkday f_wkday
 #  define a_month f_month
 #  define ampm (L_("AMPM") + 2 * (tp->tm_hour > 11))
@@ -1320,7 +1326,7 @@ __strftime_internal (s, maxsize, format, tp, tzset_called ut_argument
                  *tzset_called = true;
                }
 # endif
-             zone = tzname[tp->tm_isdst];
+             zone = tp->tm_isdst <= 1 ? tzname[tp->tm_isdst] : "?";
            }
 #endif
          if (! zone)

diff --git a/time/tst-strftime.c b/time/tst-strftime.c
index 374fba426293b2cc43f0efb0b36f0473c9e2c9c7..af3ff72faf9588126fb269b0e9080357c32b5fcb 100644 (file)
--- a/time/tst-strftime.c
+++ b/time/tst-strftime.c
@@ -4,6 +4,56 @@
 #include <time.h>
 
 
+static int
+do_bz18985 (void)
+{
+  char buf[1000];
+  struct tm ttm;
+  int rc, ret = 0;
+
+  memset (&ttm, 1, sizeof (ttm));
+  ttm.tm_zone = NULL;  /* Dereferenced directly if non-NULL.  */
+  rc = strftime (buf, sizeof (buf), "%a %A %b %B %c %z %Z", &ttm);
+
+  if (rc == 66)
+    {
+      const char expected[]
+       = "? ? ? ? ? ? 16843009 16843009:16843009:16843009 16844909 +467836 ?";
+      if (0 != strcmp (buf, expected))
+       {
+         printf ("expected:\n  %s\ngot:\n  %s\n", expected, buf);
+         ret += 1;
+       }
+    }
+  else
+    {
+      printf ("expected 66, got %d\n", rc);
+      ret += 1;
+    }
+
+  /* Check negative values as well.  */
+  memset (&ttm, 0xFF, sizeof (ttm));
+  ttm.tm_zone = NULL;  /* Dereferenced directly if non-NULL.  */
+  rc = strftime (buf, sizeof (buf), "%a %A %b %B %c %z %Z", &ttm);
+
+  if (rc == 30)
+    {
+      const char expected[] = "? ? ? ? ? ? -1 -1:-1:-1 1899  ";
+      if (0 != strcmp (buf, expected))
+       {
+         printf ("expected:\n  %s\ngot:\n  %s\n", expected, buf);
+         ret += 1;
+       }
+    }
+  else
+    {
+      printf ("expected 30, got %d\n", rc);
+      ret += 1;
+    }
+
+  return ret;
+}
+
 static struct
 {
   const char *fmt;
@@ -104,7 +154,7 @@ do_test (void)
        }
     }
 
-  return result;
+  return result + do_bz18985 ();
 }
 
 #define TEST_FUNCTION do_test ()