Hi,
I'm using libpcre's search output to validate the output of a (mostly) PCRE-compatible multipattern search library I've worked on, called liblightgrep. I wrote a pattern generator to help with this; a consequence of that is that I've run some odd patterns through libpcre, to the extent that you could say I've been fuzzing it at the pattern level. (libpcre has performed admirably, btw. I've had nothing to report until now.) There's a particular odd pattern I encountered this morning which I think is not handled properly.
When I try this with PCRE 8.33 on Fedora 20, I get what appears to be an infinite loop:
echo -n a | pcregrep -o '(?<=\Ka)'
pcregrep prints 'a', one per line, until I kill it.
It looks as though the problem has something to do with the '-o' flag, as
echo -n a | pcregrep '(?<=\Ka)'
prints 'a' once and exits.
(?<=\Ka) is obviously not a useful pattern, but reporting matches on it (rather than matching lines) shouldn't put pcregrep into an infinite loop. My test program which uses libpcre also gets into an infinite loop on this pattern, which suggests that the problem is in the library rather than in pcregrep.
Any ideas about this?
Joel Uckelman
Senior Developer
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