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Fix a LOR between the NFS server and server side krpc.

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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() would call SVC_RELEASE() with the mutex
held.  Normally this is ok, since all that happens is SVC_RELEASE()
decrements a 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() down a few lines to below where the mutex is released.

MFC after:	1 week
This commit is contained in:
Rick Macklem 2020-09-16 02:25:18 +00:00
parent b4e07e3da5
commit a5c55410b3
1 changed files with 3 additions and 2 deletions
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5
sys/fs/nfsserver/nfs_nfsdstate.c
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@ -6233,6 +6233,7 @@ nfsrv_checksequence(struct nfsrv_descript *nd, uint32_t sequenceid,
* 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 &&
@ -6245,14 +6246,14 @@ nfsrv_checksequence(struct nfsrv_descript *nd, uint32_t sequenceid,
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;