From: Eric Wong <e@80x24.org>
Date: Wed, 8 May 2019 19:04:17 +0000 (+0000)
Subject: DS: epoll: fix misordered EPOLL_CTL_DEL call
X-Git-Tag: v1.2.0~296^2
X-Git-Url: http://www.git.stargrave.org/?p=public-inbox.git;a=commitdiff_plain;h=90c5a78c8f6239b27c32b816d1cd029196ba2fe2

DS: epoll: fix misordered EPOLL_CTL_DEL call

Any operations on an fd after POSIX::close() are invalid, so
epoll_ctl will fail.  Worse off, in a multi-threaded Perl, the
fd may be reused by another thread and EPOLL_CTL_DEL can hit the
wrong file description as a result.

cf. https://rt.cpan.org/Ticket/Display.html?id=129487
---

diff --git a/lib/PublicInbox/DS.pm b/lib/PublicInbox/DS.pm
index c03bd5dd..779215c9 100644
--- a/lib/PublicInbox/DS.pm
+++ b/lib/PublicInbox/DS.pm
@@ -333,8 +333,8 @@ sub EpollEventLoop {
                 } else {
                     my $fd = $ev->[0];
                     warn "epoll() returned fd $fd w/ state $state for which we have no mapping.  removing.\n";
-                    POSIX::close($fd);
                     epoll_ctl($Epoll, EPOLL_CTL_DEL, $fd, 0);
+                    POSIX::close($fd);
                 }
                 next;
             }