From: Florian Forster <ff@octo.it>
Date: Thu, 4 May 2017 11:57:22 +0000 (+0200)
Subject: Assure that no large file descriptors are passed to FD_SET().
X-Git-Url: https://git.octo.it/?p=liboping.git;a=commitdiff_plain;h=4442437848f4d07b91c8ae1512b562299a3e6070

Assure that no large file descriptors are passed to FD_SET().

When passing a large file descriptor, on many systems large means >= 1024,
FD_SET()s behavior is undefined. Mostly, it will corrupt the stack
because an out-of-bounds bit is flipped.
---

diff --git a/src/liboping.c b/src/liboping.c
index f8c5bfb..fc9ed65 100644
--- a/src/liboping.c
+++ b/src/liboping.c
@@ -694,6 +694,7 @@ static int ping_receive_all (pingobj_t *obj)
 			if (!timerisset (ptr->timer))
 				continue;
 
+			assert (ptr->fd < FD_SETSIZE);
 			FD_SET (ptr->fd, &read_fds);
 			FD_SET (ptr->fd, &err_fds);
 			num_fds++;
@@ -1481,6 +1482,16 @@ int ping_host_add (pingobj_t *obj, const char *host)
 			ping_set_errno (obj, errno);
 			continue;
 		}
+		else if (ph->fd >= FD_SETSIZE)
+		{
+			dprintf("socket(2) returned file descriptor %d, which is above the file "
+				"descriptor limit for select(2) (FD_SETSIZE = %d)\n",
+				ph->fd, FD_SETSIZE);
+			close(ph->fd);
+			ph->fd = -1;
+			ping_set_errno(obj, EMFILE);
+			continue;
+		}
 
 		if (obj->srcaddr != NULL)
 		{