Fix catopen() Multiple unbounded stack allocations (BZ17905, CVE-2015-8779)

README.google

@@ -649,3 +649,11 @@ misc/hsearch_r.c
   https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b5cba5cff937e5336ff23380785da80cab09146c
   https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=3c9e8d9477aba0f514171bb4706670052544479b
   (stanshebs, backport)
+
+catgets/Makefile
+catgets/catgets.c
+catgets/open_catalog.c
+catgets/tst-catgets.c
+  Fix catopen() Multiple unbounded stack allocations (BZ17905, CVE-2015-8779)
+  https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=0f58539030e436449f79189b6edab17d7479796e
+  (stanshebs, backport)

catgets/Makefile

@@ -46,13 +46,14 @@ CPPFLAGS-gencat = -DNOT_IN_libc
 
 generated = de.msg test1.cat test1.h test2.cat test2.h sample.SJIS.cat \
 	    test-gencat.h
+generated += tst-catgets.mtrace tst-catgets-mem.out
 generated-dirs = de
 
-tst-catgets-ENV = NLSPATH="$(objpfx)%l/%N.cat" LANG=de
+tst-catgets-ENV = NLSPATH="$(objpfx)%l/%N.cat" LANG=de MALLOC_TRACE=$(objpfx)tst-catgets.mtrace
 
 ifeq ($(run-built-tests),yes)
 tests: $(objpfx)de/libc.cat $(objpfx)test1.cat $(objpfx)test2.cat \
-       $(objpfx)test-gencat.out
+       $(objpfx)test-gencat.out $(objpfx)tst-catgets-mem.out
 # This test just checks whether the program produces any error or not.
 # The result is not tested.
 $(objpfx)test1.cat: test1.msg $(objpfx)gencat
@@ -80,4 +81,7 @@ $(objpfx)test-gencat.out: test-gencat.sh $(objpfx)test-gencat \
 $(objpfx)sample.SJIS.cat: sample.SJIS $(objpfx)gencat
 	GCONV_PATH=$(common-objpfx)iconvdata LC_ALL=C \
 	$(built-program-cmd) -H $(objpfx)test-gencat.h < $(word 1,$^) > $@
+
+$(objpfx)tst-catgets-mem.out: $(objpfx)tst-catgets.out
+	$(common-objpfx)malloc/mtrace $(objpfx)tst-catgets.mtrace > $@
 endif

catgets/catgets.c

@@ -16,7 +16,6 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#include <alloca.h>
 #include <errno.h>
 #include <locale.h>
 #include <nl_types.h>
@@ -35,6 +34,7 @@ catopen (const char *cat_name, int flag)
   __nl_catd result;
   const char *env_var = NULL;
   const char *nlspath = NULL;
+  char *tmp = NULL;
 
   if (strchr (cat_name, '/') == NULL)
     {
@@ -54,7 +54,10 @@ catopen (const char *cat_name, int flag)
 	{
 	  /* Append the system dependent directory.  */
 	  size_t len = strlen (nlspath) + 1 + sizeof NLSPATH;
-	  char *tmp = alloca (len);
+	  tmp = malloc (len);
+
+	  if (__glibc_unlikely (tmp == NULL))
+	    return (nl_catd) -1;
 
 	  __stpcpy (__stpcpy (__stpcpy (tmp, nlspath), ":"), NLSPATH);
 	  nlspath = tmp;
@@ -65,16 +68,18 @@ catopen (const char *cat_name, int flag)
 
   result = (__nl_catd) malloc (sizeof (*result));
   if (result == NULL)
-    /* We cannot get enough memory.  */
-    return (nl_catd) -1;
-
-  if (__open_catalog (cat_name, nlspath, env_var, result) != 0)
+    {
+      /* We cannot get enough memory.  */
+      result = (nl_catd) -1;
+    }
+  else if (__open_catalog (cat_name, nlspath, env_var, result) != 0)
     {
       /* Couldn't open the file.  */
       free ((void *) result);
-      return (nl_catd) -1;
+      result = (nl_catd) -1;
     }
 
+  free (tmp);
   return (nl_catd) result;
 }
 

catgets/open_catalog.c

@@ -47,6 +47,7 @@ __open_catalog (const char *cat_name, const char *nlspath, const char *env_var,
   size_t tab_size;
   const char *lastp;
   int result = -1;
+  char *buf = NULL;
 
   if (strchr (cat_name, '/') != NULL || nlspath == NULL)
     fd = open_not_cancel_2 (cat_name, O_RDONLY);
@@ -57,23 +58,23 @@ __open_catalog (const char *cat_name, const char *nlspath, const char *env_var,
   if (__builtin_expect (bufact + (n) >= bufmax, 0))			      \
     {									      \
       char *old_buf = buf;						      \
-      bufmax += 256 + (n);						      \
-      buf = (char *) alloca (bufmax);					      \
-      memcpy (buf, old_buf, bufact);					      \
+      bufmax += (bufmax < 256 + (n)) ? 256 + (n) : bufmax;		      \
+      buf = realloc (buf, bufmax);					      \
+      if (__glibc_unlikely (buf == NULL))				      \
+	{								      \
+	  free (old_buf);						      \
+	  return -1;							      \
+	}								      \
     }
 
       /* The RUN_NLSPATH variable contains a colon separated list of
 	 descriptions where we expect to find catalogs.  We have to
 	 recognize certain % substitutions and stop when we found the
 	 first existing file.  */
-      char *buf;
       size_t bufact;
-      size_t bufmax;
+      size_t bufmax = 0;
       size_t len;
 
-      buf = NULL;
-      bufmax = 0;
-
       fd = -1;
       while (*run_nlspath != '\0')
 	{
@@ -188,7 +189,10 @@ __open_catalog (const char *cat_name, const char *nlspath, const char *env_var,
 
   /* Avoid dealing with directories and block devices */
   if (__builtin_expect (fd, 0) < 0)
-    return -1;
+    {
+      free (buf);
+      return -1;
+    }
 
   if (__builtin_expect (__fxstat64 (_STAT_VER, fd, &st), 0) < 0)
     goto close_unlock_return;
@@ -325,6 +329,7 @@ __open_catalog (const char *cat_name, const char *nlspath, const char *env_var,
   /* Release the lock again.  */
  close_unlock_return:
   close_not_cancel_no_status (fd);
+  free (buf);
 
   return result;
 }

catgets/tst-catgets.c

@@ -1,7 +1,10 @@
+#include <assert.h>
 #include <mcheck.h>
 #include <nl_types.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
+#include <sys/resource.h>
 
 
 static const char *msgs[] =
@@ -12,6 +15,33 @@ static const char *msgs[] =
 };
 #define nmsgs (sizeof (msgs) / sizeof (msgs[0]))
 
+
+/* Test for unbounded alloca.  */
+static int
+do_bz17905 (void)
+{
+  char *buf;
+  struct rlimit rl;
+  nl_catd result;
+
+  const int sz = 1024 * 1024;
+
+  getrlimit (RLIMIT_STACK, &rl);
+  rl.rlim_cur = sz;
+  setrlimit (RLIMIT_STACK, &rl);
+
+  buf = malloc (sz + 1); 
+  memset (buf, 'A', sz);
+  buf[sz] = '\0';
+  setenv ("NLSPATH", buf, 1);
+
+  result = catopen (buf, NL_CAT_LOCALE);
+  assert (result == (nl_catd) -1);
+
+  free (buf);
+  return 0;
+}
+
 #define ROUNDS 5
 
 int
@@ -62,5 +92,6 @@ main (void)
 	}
     }
 
+  result += do_bz17905 ();
   return result;
 }