> On 28 Dec. 2016, at 14:15, ex vito <ex.vitor...@gmail.com> wrote: > > Dear all, > > While working on http://twistedmatrix.com/trac/ticket/8912 and the associated > PR at https://github.com/twisted/twisted/pull/647 I hit a segmentation fault > on a test I was preparing. > > I think narrowed it down Linux + Python 2, but I'm not 100% sure. Can anyone > please confirm the code below segfaults on such environment? For > completeness, from my tests, it works fine on Linux + Python 3, and fails > with socket.error/OSError on Mac OS 10.9.5 + Python 2/3. No BSDs at hand to > try out... > > As far as I can tell, no code in Twisted uses sendmsg in the way the code is > using it. However, twisted.python.sendmsg is a public API so someone > somewhere may hit this like I just did. > > Other than looking for confirmation, I have a fix which I included two > isolated commits in the PR. Twisted project members: if this is confirmed, > maybe a ticket should be created in Trac and an independent PR created, > correct? > > Thanks in advance for any input. > Regards, > -- > exvito > > -[ cut here > ]---------------------------------------------------------------------- > > import os > import socket > import struct > import sys > > from twisted.python import sendmsg > > if __name__ == '__main__': > > # This code segfaults when running with twisted/trunk commit > # 98a3df200968b78bd3b985dfd4fb10a5b415d6fc on Linux Python 2 > # due to a bug in src/twisted/python/_sendmsg.c and glibc's > # CMSG_NXTHDR implementation. > > # get connected sockets > s1, s2 = socket.socketpair(socket.AF_UNIX) > > # two CMSGs in ancillary data (no segfault with just one) > ancillary = [ > (socket.SOL_SOCKET, sendmsg.SCM_RIGHTS, struct.pack('i', s1.fileno())), > (socket.SOL_SOCKET, sendmsg.SCM_RIGHTS, struct.pack('i', s2.fileno())), > ] > > expected = { > 2: 'Expecting to segfault.', > 3: 'Should not segfault.', > } > print expected.get(sys.version_info.major, 'Unexpected Python version.') > retval = sendmsg.sendmsg(s1, data=b'some data', ancillary=ancillary) > print 'Did not segfault.' > > -[ cut here > ]---------------------------------------------------------------------- > > > _______________________________________________ > Twisted-Python mailing list > Twisted-Python@twistedmatrix.com > http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
FWIW, for people wanting to track this down, this may be a bug in our C extension (src/twisted/python/_sendmsg.c). Python 3 uses the stdlib's functionality, which is probably why it isn't running into this. - Amber _______________________________________________ Twisted-Python mailing list Twisted-Python@twistedmatrix.com http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
