git: f6b902a4117a - stable/14 - krpc: Ref cnt the client structures for TLS upcalls

The branch stable/14 has been updated by rmacklem:

URL: https://cgit.FreeBSD.org/src/commit/?id=f6b902a4117a9893179be4e46c50358d32321301

commit f6b902a4117a9893179be4e46c50358d32321301
Author:     Rick Macklem <rmacklem@FreeBSD.org>
AuthorDate: 2024-04-27 00:55:24 +0000
Commit:     Rick Macklem <rmacklem@FreeBSD.org>
CommitDate: 2024-05-02 01:09:52 +0000

    krpc: Ref cnt the client structures for TLS upcalls
    
    A crash occurred during testing, where the client structures had
    already been free'd when the upcall thread tried to lock them.
    
    This patch acquires a reference count on both of the structures
    and these are released when the upcall is done, so that the
    structures cannot be free'd prematurely.  This happened because
    the testing is done over a very slow vpn.
    
    Found during a IETF bakeathon testing event this week.
    
    (cherry picked from commit 4ba444de708bada46a88ecac17b2f6c1dc912234)
---
 sys/rpc/clnt_vc.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/sys/rpc/clnt_vc.c b/sys/rpc/clnt_vc.c
index b4ddaec3cbdc..cc2471f95e8c 100644
--- a/sys/rpc/clnt_vc.c
+++ b/sys/rpc/clnt_vc.c
@@ -759,6 +759,7 @@ clnt_vc_control(CLIENT *cl, u_int request, void *info)
 	case CLSET_BACKCHANNEL:
 		xprt = (SVCXPRT *)info;
 		if (ct->ct_backchannelxprt == NULL) {
+			SVC_ACQUIRE(xprt);
 			xprt->xp_p2 = ct;
 			if (ct->ct_sslrefno != 0)
 				xprt->xp_tls = RPCTLS_FLAGS_HANDSHAKE;
@@ -772,9 +773,11 @@ clnt_vc_control(CLIENT *cl, u_int request, void *info)
 		ct->ct_sslusec = *p++;
 		ct->ct_sslrefno = *p;
 		if (ct->ct_sslrefno != RPCTLS_REFNO_HANDSHAKE) {
+			/* cl ref cnt is released by clnt_vc_dotlsupcall(). */
+			CLNT_ACQUIRE(cl);
 			mtx_unlock(&ct->ct_lock);
 			/* Start the kthread that handles upcalls. */
-			error = kthread_add(clnt_vc_dotlsupcall, ct,
+			error = kthread_add(clnt_vc_dotlsupcall, cl,
 			    NULL, NULL, 0, 0, "krpctls%u", thrdnum++);
 			if (error != 0)
 				panic("Can't add KRPC thread error %d", error);
@@ -874,6 +877,7 @@ clnt_vc_destroy(CLIENT *cl)
 		mtx_lock(&ct->ct_lock);
 		xprt->xp_p2 = NULL;
 		sx_xunlock(&xprt->xp_lock);
+		SVC_RELEASE(xprt);
 	}
 
 	if (ct->ct_socket) {
@@ -1274,7 +1278,8 @@ clnt_vc_upcallsdone(struct ct_data *ct)
 static void
 clnt_vc_dotlsupcall(void *data)
 {
-	struct ct_data *ct = (struct ct_data *)data;
+	CLIENT *cl = (CLIENT *)data;
+	struct ct_data *ct = (struct ct_data *)cl->cl_private;
 	enum clnt_stat ret;
 	uint32_t reterr;
 
@@ -1311,5 +1316,6 @@ clnt_vc_dotlsupcall(void *data)
 	ct->ct_rcvstate &= ~RPCRCVSTATE_UPCALLTHREAD;
 	wakeup(&ct->ct_sslrefno);
 	mtx_unlock(&ct->ct_lock);
+	CLNT_RELEASE(cl);
 	kthread_exit();
 }