Re: [ID 20010604.015] taint + comma = false insecurity

Reply-To: mjtg@cam.ac.uk
Message-Id: <E157flx-0006Uz-00@draco.cus.cam.ac.uk>

p4raw-id: //depot/perl@10459

1 files changed, 9 insertions, 5 deletions

diff --git a/pod/perlsec.pod b/pod/perlsec.pod
index 622e25fb40..87d1f7b340 100644
--- a/pod/perlsec.pod
+++ b/pod/perlsec.pod
@@ -44,8 +44,8 @@ directories, or processes, B<with the following exceptions>:
 
 =item *
 
-If you pass a list of arguments to either C<system> or C<exec>,
-the elements of that list are B<not> checked for taintedness.
+If you pass more than one argument to either C<system> or C<exec>,
+the arguments are B<not> checked for taintedness.
 
 =item *
 
@@ -53,9 +53,10 @@ Arguments to C<print> and C<syswrite> are B<not> checked for taintedness.
 
 =back
 
-Any variable set to a value
-derived from tainted data will itself be tainted, even if it is
-logically impossible for the tainted data to alter the variable.
+The value of an expression containing tainted data will itself be
+tainted, even if it is logically impossible for the tainted data to
+affect the value.
+
 Because taintedness is associated with each scalar value, some
 elements of an array can be tainted and others not.
 
@@ -107,6 +108,9 @@ For example:
     # either case the result is tainted since the list of filenames comes
     # from outside of the program.
 
+    $bad = ($arg, 23);		# $bad will be tainted
+    $arg, `true`;		# Insecure (although it isn't really)
+
 If you try to do something insecure, you will get a fatal error saying
 something like "Insecure dependency" or "Insecure $ENV{PATH}".  Note that you
 can still write an insecure B<system> or B<exec>, but only by explicitly