(decode_coding_utf_8): Reject overlong sequences.

diff --git a/src/ChangeLog b/src/ChangeLog
index 5eac57c3543bdf73c9a277a4301afd5ebcf24c02..9d7f54bddee7c4736229a5b7fa181b5b02a22ec5 100644 (file)
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,4 +1,8 @@
-2002-05-26  Dave Love  <d.love@dl.ac.uk>
+2002-05-27  Dave Love  <fx@gnu.org>
+
+       * coding.c (decode_coding_utf_8): Reject overlong sequences.
+
+2002-05-26  Dave Love  <fx@gnu.org>
 
        * coding.c: Doc fixes.
        (Fcoding_system_aliases): Fix return value.

diff --git a/src/coding.c b/src/coding.c
index a4ad9c6a5422f2f5f1528dd833bba0c94918e103..1fc59a02bb112543e04e53427f4b100533ff2990 100644 (file)
--- a/src/coding.c
+++ b/src/coding.c
@@ -1078,6 +1078,7 @@ detect_coding_utf_8 (coding, mask)
 }
 
 
+/* Fixme: deal with surrogates?  */
 static void
 decode_coding_utf_8 (coding)
      struct coding_system *coding;
@@ -1126,23 +1127,38 @@ decode_coding_utf_8 (coding)
          if (! UTF_8_EXTRA_OCTET_P (c2))
            goto invalid_code;
          if (UTF_8_2_OCTET_LEADING_P (c1))
-           c = ((c1 & 0x1F) << 6) | (c2 & 0x3F);
+           {
+             c = ((c1 & 0x1F) << 6) | (c2 & 0x3F);
+             /* Reject overlong sequences here and below.  Encoders
+                producing them are incorrect, they can be misleading,
+                and they mess up read/write invariance.  */
+             if (c < 128)
+               goto invalid_code;
+           }
          else
            {
              ONE_MORE_BYTE (c3);
              if (! UTF_8_EXTRA_OCTET_P (c3))
                goto invalid_code;
              if (UTF_8_3_OCTET_LEADING_P (c1))
-               c = (((c1 & 0xF) << 12)
-                    | ((c2 & 0x3F) << 6) | (c3 & 0x3F));
+               {
+                 c = (((c1 & 0xF) << 12)
+                      | ((c2 & 0x3F) << 6) | (c3 & 0x3F));
+                 if (c < 0x800)
+                   goto invalid_code;
+               }
              else
                {
                  ONE_MORE_BYTE (c4);
                  if (! UTF_8_EXTRA_OCTET_P (c4))
                    goto invalid_code;
                  if (UTF_8_4_OCTET_LEADING_P (c1))
+                   {
                    c = (((c1 & 0x7) << 18) | ((c2 & 0x3F) << 12)
                         | ((c3 & 0x3F) << 6) | (c4 & 0x3F));
+                   if (c < 0x10000)
+                     goto invalid_code;
+                   }
                  else
                    {
                      ONE_MORE_BYTE (c5);
@@ -1153,7 +1169,7 @@ decode_coding_utf_8 (coding)
                          c = (((c1 & 0x3) << 24) | ((c2 & 0x3F) << 18)
                               | ((c3 & 0x3F) << 12) | ((c4 & 0x3F) << 6)
                               | (c5 & 0x3F));
-                         if (c > MAX_CHAR)
+                         if ((c > MAX_CHAR) || (c < 0x200000))
                            goto invalid_code;
                        }
                      else