Avoid strtol on non-null-terminated data.

Technically, `strtol` can only be used with C strings terminated with
`\0`.  CID data is not generally null-terminated and often does not
contain a `\0` if it is hex-encoded.  AddressSanitizer with `ASAN_OPTIONS`
containing `strict_string_checks=1` verifies this by using an adversarial
`strtol` that always reads to the terminating `\0`.

To avoid undefined behavior from `strtol` in `cid_parser_new`, use the
parser to parse the tokens instead of attempting to parse them ad-hoc.
This will internally use `PS_Conv_Strtol` to parse the integer, which
respects the parser's limits and directly implements the PostScript
parsing rules for integers.

* src/cid/cidparse.c (cid_parser_new): Use the parser to parse the
tokens.

Fixes: https://bugs.chromium.org/p/chromium/issues/detail?id=1420329

1 files changed, 11 insertions, 5 deletions

diff --git a/src/cid/cidparse.c b/src/cid/cidparse.c
index 16889db9b..171a88621 100644
--- a/src/cid/cidparse.c
+++ b/src/cid/cidparse.c
@@ -214,18 +214,24 @@
            cur <= limit - STARTDATA_LEN                            &&
            ft_strncmp( (char*)cur, STARTDATA, STARTDATA_LEN ) == 0 )
       {
-        if ( ft_strncmp( (char*)arg1, "(Hex)", 5 ) == 0 )
-        {
-          FT_Long  tmp = ft_strtol( (const char *)arg2, NULL, 10 );
+        T1_TokenRec  type_token;
+        FT_Long      binary_length;
 
 
-          if ( tmp < 0 )
+        parser->root.cursor = arg1;
+        cid_parser_to_token( parser, &type_token );
+        if ( type_token.limit - type_token.start == 5              &&
+             ft_memcmp( (char*)type_token.start, "(Hex)", 5 ) == 0 )
+        {
+          parser->root.cursor = arg2;
+          binary_length = cid_parser_to_int( parser );
+          if ( binary_length < 0 )
           {
             FT_ERROR(( "cid_parser_new: invalid length of hex data\n" ));
             error = FT_THROW( Invalid_File_Format );
           }
           else
-            parser->binary_length = (FT_ULong)tmp;
+            parser->binary_length = (FT_ULong)binary_length;
         }
 
         goto Exit;