Date: Wed, 6 Jun 2018 01:30:49 +0000 (UTC) From: Rick Macklem <rmacklem@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r334699 - stable/10/sys/fs/nfsserver Message-ID: <201806060130.w561UnSd044170@repo.freebsd.org>
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Author: rmacklem Date: Wed Jun 6 01:30:48 2018 New Revision: 334699 URL: https://svnweb.freebsd.org/changeset/base/334699 Log: MFC: r334396 Strengthen locking for the NFSv4.1 server DestroySession operation. If a client did a DestroySession on a session while it was still in use, the server might try to use the session structure after it is free'd. I think the client has violated RFC5661 if it does this, but this patch makes DestroySession block all other nfsd threads so no thread could be using the session when it is free'd. After the DestroySession, nfsd threads will not be able to find the session. The patch also adds a check for nd_sessionid being set, although if that was not the case it would have been all 0s and unlikely to have a false match. This might fix the crashes described in PR#228497 for the FreeNAS server. PR: 228497 Modified: stable/10/sys/fs/nfsserver/nfs_nfsdstate.c Directory Properties: stable/10/ (props changed) Modified: stable/10/sys/fs/nfsserver/nfs_nfsdstate.c ============================================================================== --- stable/10/sys/fs/nfsserver/nfs_nfsdstate.c Wed Jun 6 01:21:33 2018 (r334698) +++ stable/10/sys/fs/nfsserver/nfs_nfsdstate.c Wed Jun 6 01:30:48 2018 (r334699) @@ -5938,17 +5938,32 @@ nfsrv_findsession(uint8_t *sessionid) int nfsrv_destroysession(struct nfsrv_descript *nd, uint8_t *sessionid) { - int error, samesess; + int error, igotlock, samesess; samesess = 0; - if (!NFSBCMP(sessionid, nd->nd_sessionid, NFSX_V4SESSIONID)) { + if (!NFSBCMP(sessionid, nd->nd_sessionid, NFSX_V4SESSIONID) && + (nd->nd_flag & ND_HASSEQUENCE) != 0) { samesess = 1; if ((nd->nd_flag & ND_LASTOP) == 0) return (NFSERR_BADSESSION); } + + /* Lock out other nfsd threads */ + NFSLOCKV4ROOTMUTEX(); + nfsv4_relref(&nfsv4rootfs_lock); + do { + igotlock = nfsv4_lock(&nfsv4rootfs_lock, 1, NULL, + NFSV4ROOTLOCKMUTEXPTR, NULL); + } while (igotlock == 0); + NFSUNLOCKV4ROOTMUTEX(); + error = nfsrv_freesession(NULL, sessionid); if (error == 0 && samesess != 0) nd->nd_flag &= ~ND_HASSEQUENCE; + + NFSLOCKV4ROOTMUTEX(); + nfsv4_unlock(&nfsv4rootfs_lock, 1); + NFSUNLOCKV4ROOTMUTEX(); return (error); }
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