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Date:      Mon, 13 Apr 2020 19:22:05 +0000 (UTC)
From:      Mark Johnston <markj@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r359893 - head/sys/kern
Message-ID:  <202004131922.03DJM56L003792@repo.freebsd.org>
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Author: markj
Date: Mon Apr 13 19:22:05 2020
New Revision: 359893
URL: https://svnweb.freebsd.org/changeset/base/359893

Log:
  Fix sendto() on unconnected SOCK_STREAM/SEQPACKET unix sockets.
  
  Previously the unpcb pointer of the newly connected remote socket was
  not initialized correctly, so attempting to lock it would result in a
  null pointer dereference.
  
  Reported by:	syzkaller
  MFC after:	1 week
  Sponsored by:	The FreeBSD Foundation

Modified:
  head/sys/kern/uipc_usrreq.c

Modified: head/sys/kern/uipc_usrreq.c
==============================================================================
--- head/sys/kern/uipc_usrreq.c	Mon Apr 13 19:20:39 2020	(r359892)
+++ head/sys/kern/uipc_usrreq.c	Mon Apr 13 19:22:05 2020	(r359893)
@@ -1138,25 +1138,29 @@ uipc_send(struct socket *so, int flags, struct mbuf *m
 	case SOCK_STREAM:
 		if ((so->so_state & SS_ISCONNECTED) == 0) {
 			if (nam != NULL) {
-				if ((error = connect_internal(so, nam, td)))
+				error = connect_internal(so, nam, td);
+				if (error != 0)
 					break;
-			} else  {
+			} else {
 				error = ENOTCONN;
 				break;
 			}
-		} else if ((unp2 = unp->unp_conn) == NULL) {
+		} else {
+			UNP_PCB_LOCK(unp);
+		}
+
+		if ((unp2 = unp->unp_conn) == NULL) {
+			UNP_PCB_UNLOCK(unp);
 			error = ENOTCONN;
 			break;
 		} else if (so->so_snd.sb_state & SBS_CANTSENDMORE) {
+			UNP_PCB_UNLOCK(unp);
 			error = EPIPE;
 			break;
-		} else {
-			UNP_PCB_LOCK(unp);
-			if ((unp2 = unp->unp_conn) == NULL) {
-				UNP_PCB_UNLOCK(unp);
-				error = ENOTCONN;
-				break;
-			}
+		} else if ((unp2 = unp->unp_conn) == NULL) {
+			UNP_PCB_UNLOCK(unp);
+			error = ENOTCONN;
+			break;
 		}
 		unp_pcb_owned_lock2(unp, unp2, freed);
 		UNP_PCB_UNLOCK(unp);
@@ -1198,15 +1202,11 @@ uipc_send(struct socket *so, int flags, struct mbuf *m
 				sbappend_locked(&so2->so_rcv, m, flags);
 			break;
 
-		case SOCK_SEQPACKET: {
-			const struct sockaddr *from;
-
-			from = &sun_noname;
+		case SOCK_SEQPACKET:
 			if (sbappendaddr_nospacecheck_locked(&so2->so_rcv,
-			    from, m, control))
+			    &sun_noname, m, control))
 				control = NULL;
 			break;
-			}
 		}
 
 		mbcnt = so2->so_rcv.sb_mbcnt;

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