On Thursday, August 23, 2012 12:17:22 PM Andres Freund wrote: > Hi, > > While debugging an instance of this bug I noticed that plperlu always > removes the SIGFPE handler and sets it to ignore: > > > andres@awork2:~$ psql -p 5435 -U postgres -h /var/run/postgresql test > Timing is on. > psql (9.1devel, server 9.1.5) > Type "help" for help. > > test=# SELECT pg_backend_pid(); > pg_backend_pid > ---------------- > 9287 > > root@awork2:/home/andres# grep -E '^Sig(Cgt|Ign)' /proc/9287/status|awk > '{print $2}' > 0000000001301800 > 0000000180006287 > > test=# DO LANGUAGE plperlu $$$$; > > root@awork2:/home/andres# grep -E '^Sig(Cgt|Ign)' /proc/9287/status|awk > '{print $2}' > 0000000001301880 > 0000000180006207 > > Note the 8'th bit being unset in SigCgt and set in SigIgn. Thats SIGFPE... > > Not sure how relevant this really is, but it could cause errors to be > ignored...
In fact it can be used to crash the server: test=# SELECT (-2^31)::int/-1; ERROR: floating-point exception DETAIL: An invalid floating-point operation was signaled. This probably means an out-of-range result or an invalid operation, such as division by zero. test=# DO LANGUAGE plperl $$$$; DO Time: 172.235 ms test=# SELECT (-2^31)::int/-1; server closed the connection unexpectedly This probably means the server terminated abnormally before or while processing the request. The connection to the server was lost. Attempting reset: Failed. Greetings, Andres -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers