From aff5a49b0e75dd08428a88c05d98f39885556c8b Mon Sep 17 00:00:00 2001 From: David Gibson Date: Fri, 6 Sep 2024 15:17:10 +1000 Subject: [PATCH] udp: Handle more error conditions in udp_sock_errs() udp_sock_errs() reads out everything in the socket error queue. However we've seen some cases[0] where an EPOLLERR event is active, but there isn't anything in the queue. One possibility is that the error is reported instead by the SO_ERROR sockopt. Check for that case and report it as best we can. If we still get an EPOLLERR without visible error, we have no way to clear the error state, so treat it as an unrecoverable error. [0] https://github.com/containers/podman/issues/23686#issuecomment-2324945010 Link: https://bugs.passt.top/show_bug.cgi?id=95 Signed-off-by: David Gibson Signed-off-by: Stefano Brivio --- udp.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/udp.c b/udp.c index 85a14de..ae91027 100644 --- a/udp.c +++ b/udp.c @@ -450,7 +450,8 @@ static int udp_sock_recverr(int s) static int udp_sock_errs(const struct ctx *c, int s, uint32_t events) { unsigned n_err = 0; - int rc; + socklen_t errlen; + int rc, err; ASSERT(!c->no_udp); @@ -464,6 +465,24 @@ static int udp_sock_errs(const struct ctx *c, int s, uint32_t events) if (rc < 0) return -1; /* error reading error, unrecoverable */ + errlen = sizeof(err); + if (getsockopt(s, SOL_SOCKET, SO_ERROR, &err, &errlen) < 0 || + errlen != sizeof(err)) { + err_perror("Error reading SO_ERROR"); + return -1; /* error reading error, unrecoverable */ + } + + if (err) { + debug("Unqueued error on UDP socket %i: %s", s, strerror(err)); + n_err++; + } + + if (!n_err) { + /* EPOLLERR, but no errors to clear !? */ + err("EPOLLERR event without reported errors on socket %i", s); + return -1; /* no way to clear, unrecoverable */ + } + return n_err; }