154207 – security/p5-Crypt-RandPasswd: patch for method invocation bug in Crypt::RandPasswd->random_chars_in_range()

If an external caller invokes the the method Crypt::RandPasswd->random_chars_in_range(), Perl prepends the object name to the function's argument list.  This causes the local variables $minlen, $maxlen, $lo_char, and $hi_char to be set incorrectly ($minlen is set to the object name, $maxlen is set to what should have been the minimum length, $lo_char is set to what should have been the maximum length, and $hi_char is set to what should have been the first character in the given range), so that the method returns an incorrect result.

When random_chars_in_range() is called from within the module (e.g., by the letters() method), Perl does not modify the argument list, so the random_chars_in_range() method works as documented.

Fix: Apply this patch to the Crypt::RandPasswd sources, which in random_chars_in_range(), adds a check to the argument list length prior to parsing, and if it is greater than 4 items, shifts the list down by one:



sub random_chars_in_range($$$$) {
+     @_ > 4 and shift;
      my( $minlen, $maxlen, $lo_char, $hi_char ) = @_;

      $minlen <= $maxlen or die "minlen $minlen is greater than maxlen $maxlen";--amCEPnhCfL1pX7mGstjY33ObCLuITbFTH7kc27dMtqS5S3Xp
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--- Crypt-RandPasswd-0.02/lib/Crypt/RandPasswd.pm.orig  2011-01-20 15:12:21.305822700 -0500
+++ Crypt-RandPasswd-0.02/lib/Crypt/RandPasswd.pm       2011-01-21 10:55:30.872462500 -0500
@@ -1466,6 +1466,7 @@
 =cut
How-To-Repeat: These two commands should have an equivalent result (32 random lower-case letters):

perl -MCrypt::RandPasswd -e 'print Crypt::RandPasswd->letters(32,32),"\n";'

perl -MCrypt::RandPasswd -e 'print Crypt::RandPasswd->random_chars_in_range(32,32, "a" => "z"),"\n";'

However, the second command will result in a random string from zero to 32 characters long taken from the set ASCII code 32 (space) through the letter "a".