svn commit: r361037 - head/sys/kern

[Konstantin Belousov]

Author: kib
Date: Thu May 14 17:54:08 2020
New Revision: 361037
URL: https://svnweb.freebsd.org/changeset/base/361037

Log:
  Fix spurious ENOTCONN from closed unix domain socket other' side.
  
  Sometimes, when doing read(2) over unix domain socket, for which the
  other side socket was closed, read(2) returns -1/ENOTCONN instead of
  EOF AKA zero-size read. This is because soreceive_generic() does not
  lock socket when testing the so_state SS_ISCONNECTED|SS_ISCONNECTING
  flags. It could end up that we do not observe so->so_rcv.sb_state bit
  SBS_CANTRCVMORE, and then miss SS_ flags.
  
  Change the test to check that the socket was never connected before
  returning ENOTCONN, by adding all state bits for connected.
  
  Reported and tested by:	pho
  In collaboration with:	markj
  Sponsored by:	The FreeBSD Foundation
  MFC after:	1 week
  Differential revision:	https://reviews.freebsd.org/D24819

Modified:
  head/sys/kern/uipc_socket.c

Modified: head/sys/kern/uipc_socket.c
==============================================================================
--- head/sys/kern/uipc_socket.c	Thu May 14 17:52:29 2020	(r361036)
+++ head/sys/kern/uipc_socket.c	Thu May 14 17:54:08 2020	(r361037)
@@ -1969,8 +1969,9 @@ restart:
 				m = so->so_rcv.sb_mb;
 				goto dontblock;
 			}
-		if ((so->so_state & (SS_ISCONNECTED|SS_ISCONNECTING)) == 0 &&
-		    (so->so_proto->pr_flags & PR_CONNREQUIRED)) {
+		if ((so->so_state & (SS_ISCONNECTING | SS_ISCONNECTED |
+		    SS_ISDISCONNECTING | SS_ISDISCONNECTED)) == 0 &&
+		    (so->so_proto->pr_flags & PR_CONNREQUIRED) != 0) {
 			SOCKBUF_UNLOCK(&so->so_rcv);
 			error = ENOTCONN;
 			goto release;