From c101b576828471a84228eb01407efe2b370b0603 Mon Sep 17 00:00:00 2001
From: Michael Lotz <mmlr@mlotz.ch>
Date: Tue, 3 Apr 2018 23:50:39 +0200
Subject: [PATCH] kernel: Implement FD limit check for select/poll.

The amount of FDs that can be selected/polled needs to be limited by
the RLIMIT_NOFILES.
---
 src/system/kernel/wait_for_objects.cpp | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/system/kernel/wait_for_objects.cpp b/src/system/kernel/wait_for_objects.cpp
index dbb6ffdb54..edc3b8a286 100644
--- a/src/system/kernel/wait_for_objects.cpp
+++ b/src/system/kernel/wait_for_objects.cpp
@@ -906,6 +906,15 @@ _kern_wait_for_objects(object_wait_info* infos, int numInfos, uint32 flags,
 //	#pragma mark - User syscalls
 
 
+static bool
+check_max_fds(int numFDs)
+{
+	struct io_context *context = get_current_io_context(false);
+	MutexLocker(&context->io_mutex);
+	return numFDs <= context->table_size;
+}
+
+
 ssize_t
 _user_select(int numFDs, fd_set *userReadSet, fd_set *userWriteSet,
 	fd_set *userErrorSet, bigtime_t timeout, const sigset_t *userSigMask)
@@ -917,7 +926,7 @@ _user_select(int numFDs, fd_set *userReadSet, fd_set *userWriteSet,
 
 	syscall_restart_handle_timeout_pre(timeout);
 
-	if (numFDs < 0)
+	if (numFDs < 0 || !check_max_fds(numFDs))
 		return B_BAD_VALUE;
 
 	if ((userReadSet != NULL && !IS_USER_ADDRESS(userReadSet))
@@ -1013,6 +1022,9 @@ _user_poll(struct pollfd *userfds, int numFDs, bigtime_t timeout)
 			? syscall_restart_handle_timeout_post(result, timeout) : result;
 	}
 
+	if (!check_max_fds(numFDs))
+		return B_BAD_VALUE;
+
 	// copy parameters
 	if (userfds == NULL || !IS_USER_ADDRESS(userfds))
 		return B_BAD_ADDRESS;