Wierdly, it seems that in perl 5.8.8, either of packing and unpacking with "B*" untaints, unpacking with "N*" untaints; but packing with "N*" or packing and unpacking with "C*" or "a*" doesn't untaint a scalar. I've no idea what the correct behaiviour should be.

Not really related, but note that this command doesn't raise an insecure dependency error: 

perl -wTe '() = unpack $ARGV[0], 1e9;' p

[download]
it segfaults.

However, the result of such an unpack is tainted, as can be seen from the error from this command. 

perl -wTe '$z = pack "p", "hi\n"; $r = unpack $ARGV[0], $z; eval $r;' 
+p

[download]

Update: I forgot to say that I found this bug when re-examining Re: What's your favourite method of untainting?.

Update: see perlbug ticket #52552.

In reply to Re: pack() untaints data : bug or undocumented Perl 5.10 feature? by ambrus
in thread pack() untaints data : bug or undocumented Perl 5.10 feature? by mr_mischief

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