From a34be19f17fcf7a15d64fc241c73ead993ba89e6 Mon Sep 17 00:00:00 2001 From: Jacob Champion Date: Wed, 6 Aug 2025 15:18:08 -0700 Subject: [PATCH v4 2/5] oauth: Ensure unused socket registrations are removed If Curl needs to switch the direction of a socket's registration (e.g. from CURL_POLL_IN to CURL_POLL_OUT), it expects the old registration to be discarded. For epoll, this happened via EPOLL_CTL_MOD, but for kqueue, the old registration would remain if it was not explicitly removed by Curl. Explicitly remove the opposite-direction event during registrations. (If that event doesn't exist, we'll just get an ENOENT, which will be ignored by the same code that handles CURL_POLL_REMOVE.) A few assertions are also added to strengthen the relationship between the number of events added, the number of events pulled off the queue, and the lengths of the kevent arrays. Reviewed-by: Thomas Munro Backpatch-through: 18 Discussion: https://postgr.es/m/CAOYmi+nDZxJHaWj9_jRSyf8uMToCADAmOfJEggsKW-kY7aUwHA@mail.gmail.com --- src/interfaces/libpq-oauth/oauth-curl.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) diff --git a/src/interfaces/libpq-oauth/oauth-curl.c b/src/interfaces/libpq-oauth/oauth-curl.c index 433135cb86d..97c33299a79 100644 --- a/src/interfaces/libpq-oauth/oauth-curl.c +++ b/src/interfaces/libpq-oauth/oauth-curl.c @@ -1291,22 +1291,31 @@ register_socket(CURL *curl, curl_socket_t socket, int what, void *ctx, return 0; #elif defined(HAVE_SYS_EVENT_H) - struct kevent ev[2] = {0}; + struct kevent ev[2]; struct kevent ev_out[2]; struct timespec timeout = {0}; int nev = 0; int res; + /* + * We don't know which of the events is currently registered, perhaps + * both, so we always try to remove unneeded events. This means we need to + * tolerate ENOENT below. + */ switch (what) { case CURL_POLL_IN: EV_SET(&ev[nev], socket, EVFILT_READ, EV_ADD | EV_RECEIPT, 0, 0, 0); nev++; + EV_SET(&ev[nev], socket, EVFILT_WRITE, EV_DELETE | EV_RECEIPT, 0, 0, 0); + nev++; break; case CURL_POLL_OUT: EV_SET(&ev[nev], socket, EVFILT_WRITE, EV_ADD | EV_RECEIPT, 0, 0, 0); nev++; + EV_SET(&ev[nev], socket, EVFILT_READ, EV_DELETE | EV_RECEIPT, 0, 0, 0); + nev++; break; case CURL_POLL_INOUT: @@ -1317,12 +1326,6 @@ register_socket(CURL *curl, curl_socket_t socket, int what, void *ctx, break; case CURL_POLL_REMOVE: - - /* - * We don't know which of these is currently registered, perhaps - * both, so we try to remove both. This means we need to tolerate - * ENOENT below. - */ EV_SET(&ev[nev], socket, EVFILT_READ, EV_DELETE | EV_RECEIPT, 0, 0, 0); nev++; EV_SET(&ev[nev], socket, EVFILT_WRITE, EV_DELETE | EV_RECEIPT, 0, 0, 0); @@ -1334,7 +1337,10 @@ register_socket(CURL *curl, curl_socket_t socket, int what, void *ctx, return -1; } - res = kevent(actx->mux, ev, nev, ev_out, lengthof(ev_out), &timeout); + Assert(nev <= lengthof(ev)); + Assert(nev <= lengthof(ev_out)); + + res = kevent(actx->mux, ev, nev, ev_out, nev, &timeout); if (res < 0) { actx_error(actx, "could not modify kqueue: %m"); -- 2.34.1