BUG/MAJOR: ev_select: disable the select() poller if maxsock > FD_SETSIZE
Some recent glibc updates have added controls on FD_SET/FD_CLR/FD_ISSET
that crash the program if it tries to use a file descriptor larger than
FD_SETSIZE.
For this reason, we now control the compatibility between global.maxsock
and FD_SETSIZE, and refuse to use select() if there too many FDs are
expected to be used. Note that on Solaris, FD_SETSIZE is already forced
to 65536, and that FreeBSD and OpenBSD allow it to be redefined, though
this is not needed thanks to kqueue which is much more efficient.
In practice, since poll() is enabled on all targets, it should not cause
any problem, unless it is explicitly disabled.
This change must be backported to 1.4 because the crashes caused by glibc
have already been reported on this version.
diff --git a/src/ev_select.c b/src/ev_select.c
index dba5928..946fbfd 100644
--- a/src/ev_select.c
+++ b/src/ev_select.c
@@ -191,6 +191,10 @@
int fd_set_bytes;
p->private = NULL;
+
+ if (global.maxsock > FD_SETSIZE)
+ goto fail_revt;
+
fd_set_bytes = sizeof(fd_set) * (global.maxsock + FD_SETSIZE - 1) / FD_SETSIZE;
if ((tmp_evts[DIR_RD] = (fd_set *)calloc(1, fd_set_bytes)) == NULL)
@@ -238,6 +242,9 @@
*/
REGPRM1 static int _do_test(struct poller *p)
{
+ if (global.maxsock > FD_SETSIZE)
+ return 0;
+
return 1;
}
diff --git a/src/haproxy.c b/src/haproxy.c
index 92e25c2..1782bce 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -795,7 +795,16 @@
list_pollers(stderr);
if (!init_pollers()) {
- Alert("No polling mechanism available.\n");
+ Alert("No polling mechanism available.\n"
+ " It is likely that haproxy was built with TARGET=generic and that FD_SETSIZE\n"
+ " is too low on this platform to support maxconn and the number of listeners\n"
+ " and servers. You should rebuild haproxy specifying your system using TARGET=\n"
+ " in order to support other polling systems (poll, epoll, kqueue) or reduce the\n"
+ " global maxconn setting to accomodate the system's limitation. For reference,\n"
+ " FD_SETSIZE=%d on this system, global.maxconn=%d resulting in a maximum of\n"
+ " %d file descriptors. You should thus reduce global.maxconn by %d. Also,\n"
+ " check build settings using 'haproxy -vv'.\n\n",
+ FD_SETSIZE, global.maxconn, global.maxsock, (global.maxsock + 1 - FD_SETSIZE) / 2);
exit(1);
}
if (global.mode & (MODE_VERBOSE|MODE_DEBUG)) {