From 3ee23a0a5a8c2261e788acbee67722fcbecbea28 Mon Sep 17 00:00:00 2001
From: Hitendra Prajapati <hprajapati@mvista.com>
Date: Wed, 27 Jul 2022 17:34:21 +0530
Subject: [PATCH] CVE-2021-46828

Upstream-Status: Backport [http://git.linux-nfs.org/?p=steved/libtirpc.git;a=commit;h=86529758570cef4c73fb9b9c4104fdc510f701ed}
CVE: CVE-2021-46828
Signed-off-by: Hitendra Prajapati <hprajapati@mvista.com>
---
 src/svc.c    | 17 +++++++++++++-
 src/svc_vc.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 77 insertions(+), 2 deletions(-)

diff --git a/src/svc.c b/src/svc.c
index 6db164b..3a8709f 100644
--- a/src/svc.c
+++ b/src/svc.c
@@ -57,7 +57,7 @@
 
 #define max(a, b) (a > b ? a : b)
 
-static SVCXPRT **__svc_xports;
+SVCXPRT **__svc_xports;
 int __svc_maxrec;
 
 /*
@@ -194,6 +194,21 @@ __xprt_do_unregister (xprt, dolock)
     rwlock_unlock (&svc_fd_lock);
 }
 
+int
+svc_open_fds()
+{
+	int ix;
+	int nfds = 0;
+
+	rwlock_rdlock (&svc_fd_lock);
+	for (ix = 0; ix < svc_max_pollfd; ++ix) {
+		if (svc_pollfd[ix].fd != -1)
+			nfds++;
+	}
+	rwlock_unlock (&svc_fd_lock);
+	return (nfds);
+}
+
 /*
  * Add a service program to the callout list.
  * The dispatch routine will be called when a rpc request for this
diff --git a/src/svc_vc.c b/src/svc_vc.c
index f1d9f00..3dc8a75 100644
--- a/src/svc_vc.c
+++ b/src/svc_vc.c
@@ -64,6 +64,8 @@
 
 
 extern rwlock_t svc_fd_lock;
+extern SVCXPRT **__svc_xports;
+extern int svc_open_fds();
 
 static SVCXPRT *makefd_xprt(int, u_int, u_int);
 static bool_t rendezvous_request(SVCXPRT *, struct rpc_msg *);
@@ -82,6 +84,7 @@ static void svc_vc_ops(SVCXPRT *);
 static bool_t svc_vc_control(SVCXPRT *xprt, const u_int rq, void *in);
 static bool_t svc_vc_rendezvous_control (SVCXPRT *xprt, const u_int rq,
 				   	     void *in);
+static int __svc_destroy_idle(int timeout);
 
 struct cf_rendezvous { /* kept in xprt->xp_p1 for rendezvouser */
 	u_int sendsize;
@@ -313,13 +316,14 @@ done:
 	return (xprt);
 }
 
+
 /*ARGSUSED*/
 static bool_t
 rendezvous_request(xprt, msg)
 	SVCXPRT *xprt;
 	struct rpc_msg *msg;
 {
-	int sock, flags;
+	int sock, flags, nfds, cnt;
 	struct cf_rendezvous *r;
 	struct cf_conn *cd;
 	struct sockaddr_storage addr;
@@ -379,6 +383,16 @@ again:
 
 	gettimeofday(&cd->last_recv_time, NULL);
 
+	nfds = svc_open_fds();
+	if (nfds >= (_rpc_dtablesize() / 5) * 4) {
+		/* destroy idle connections */
+		cnt = __svc_destroy_idle(15);
+		if (cnt == 0) {
+			/* destroy least active */
+			__svc_destroy_idle(0);
+		}
+	}
+
 	return (FALSE); /* there is never an rpc msg to be processed */
 }
 
@@ -820,3 +834,49 @@ __svc_clean_idle(fd_set *fds, int timeout, bool_t cleanblock)
 {
 	return FALSE;
 }
+
+static int
+__svc_destroy_idle(int timeout)
+{
+	int i, ncleaned = 0;
+	SVCXPRT *xprt, *least_active;
+	struct timeval tv, tdiff, tmax;
+	struct cf_conn *cd;
+
+	gettimeofday(&tv, NULL);
+	tmax.tv_sec = tmax.tv_usec = 0;
+	least_active = NULL;
+	rwlock_wrlock(&svc_fd_lock);
+
+	for (i = 0; i <= svc_max_pollfd; i++) {
+		if (svc_pollfd[i].fd == -1)
+			continue;
+		xprt = __svc_xports[i];
+		if (xprt == NULL || xprt->xp_ops == NULL ||
+			xprt->xp_ops->xp_recv != svc_vc_recv)
+			continue;
+		cd = (struct cf_conn *)xprt->xp_p1;
+		if (!cd->nonblock)
+			continue;
+		if (timeout == 0) {
+			timersub(&tv, &cd->last_recv_time, &tdiff);
+			if (timercmp(&tdiff, &tmax, >)) {
+				tmax = tdiff;
+				least_active = xprt;
+			}
+			continue;
+		}
+		if (tv.tv_sec - cd->last_recv_time.tv_sec > timeout) {
+			__xprt_unregister_unlocked(xprt);
+			__svc_vc_dodestroy(xprt);
+			ncleaned++;
+		}
+	}
+	if (timeout == 0 && least_active != NULL) {
+		__xprt_unregister_unlocked(least_active);
+		__svc_vc_dodestroy(least_active);
+		ncleaned++;
+	}
+	rwlock_unlock(&svc_fd_lock);
+	return (ncleaned);
+}
-- 
2.25.1