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Date:      Thu, 24 Sep 2020 16:21:31 +0000 (UTC)
From:      Rick Macklem <rmacklem@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-releng@freebsd.org
Subject:   svn commit: r366120 - releng/12.2/sys/fs/nfsserver
Message-ID:  <202009241621.08OGLVik030660@repo.freebsd.org>
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Author: rmacklem
Date: Thu Sep 24 16:21:30 2020
New Revision: 366120
URL: https://svnweb.freebsd.org/changeset/base/366120

Log:
  MFS: r366050, r366117
  Fix a LOR between the NFS server and server side krpc.
  
  Recent testing of the NFS-over-TLS code found a LOR between the mutex lock
  used for sessions and the sleep lock used for server side krpc socket
  structures.
  The code in nfsrv_checksequence() and nfsrv_bindconnsess() would call
  SVC_RELEASE() with mutex(es) held.  Normally this is ok, since
  all that happens is SVC_RELEASE() decrements the reference count.
  However, if the socket has just been shut
  down, SVC_RELEASE() drops the reference count to 0 and acquires a sleep
  lock during destruction of the server side krpc structure.
  
  This patch fixes the problem by moving the SVC_RELEASE() call in
  nfsrv_checksequence() and nfsrv_bindconnsess() down a few lines to
  below where the mutex(es) are released.
  
  Approved by:	re (gjb)

Modified:
  releng/12.2/sys/fs/nfsserver/nfs_nfsdstate.c
Directory Properties:
  releng/12.2/   (props changed)

Modified: releng/12.2/sys/fs/nfsserver/nfs_nfsdstate.c
==============================================================================
--- releng/12.2/sys/fs/nfsserver/nfs_nfsdstate.c	Thu Sep 24 16:11:53 2020	(r366119)
+++ releng/12.2/sys/fs/nfsserver/nfs_nfsdstate.c	Thu Sep 24 16:21:30 2020	(r366120)
@@ -6214,6 +6214,7 @@ nfsrv_checksequence(struct nfsrv_descript *nd, uint32_
 	 * bound as well, do the implicit binding unless a
 	 * BindConnectiontoSession has already been done on the session.
 	 */
+	savxprt = NULL;
 	if (sep->sess_clp->lc_req.nr_client != NULL &&
 	    sep->sess_cbsess.nfsess_xprt != nd->nd_xprt &&
 	    (sep->sess_crflags & NFSV4CRSESS_CONNBACKCHAN) != 0 &&
@@ -6226,14 +6227,14 @@ nfsrv_checksequence(struct nfsrv_descript *nd, uint32_
 		    sep->sess_clp->lc_req.nr_client->cl_private;
 		nd->nd_xprt->xp_idletimeout = 0;	/* Disable timeout. */
 		sep->sess_cbsess.nfsess_xprt = nd->nd_xprt;
-		if (savxprt != NULL)
-			SVC_RELEASE(savxprt);
 	}
 
 	*sflagsp = 0;
 	if (sep->sess_clp->lc_req.nr_client == NULL)
 		*sflagsp |= NFSV4SEQ_CBPATHDOWN;
 	NFSUNLOCKSESSION(shp);
+	if (savxprt != NULL)
+		SVC_RELEASE(savxprt);
 	if (error == NFSERR_EXPIRED) {
 		*sflagsp |= NFSV4SEQ_EXPIREDALLSTATEREVOKED;
 		error = 0;
@@ -6404,6 +6405,7 @@ nfsrv_bindconnsess(struct nfsrv_descript *nd, uint8_t 
 	int error;
 
 	error = 0;
+	savxprt = NULL;
 	shp = NFSSESSIONHASH(sessionid);
 	NFSLOCKSTATE();
 	NFSLOCKSESSION(shp);
@@ -6431,8 +6433,6 @@ nfsrv_bindconnsess(struct nfsrv_descript *nd, uint8_t 
 				/* Disable idle timeout. */
 				nd->nd_xprt->xp_idletimeout = 0;
 				sep->sess_cbsess.nfsess_xprt = nd->nd_xprt;
-				if (savxprt != NULL)
-					SVC_RELEASE(savxprt);
 				sep->sess_crflags |= NFSV4CRSESS_CONNBACKCHAN;
 				clp->lc_flags |= LCL_DONEBINDCONN;
 				if (*foreaftp == NFSCDFS4_BACK)
@@ -6459,6 +6459,8 @@ nfsrv_bindconnsess(struct nfsrv_descript *nd, uint8_t 
 		error = NFSERR_BADSESSION;
 	NFSUNLOCKSESSION(shp);
 	NFSUNLOCKSTATE();
+	if (savxprt != NULL)
+		SVC_RELEASE(savxprt);
 	return (error);
 }

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