Commit d8a1a000 authored by Trond Myklebust's avatar Trond Myklebust Committed by J. Bruce Fields
Browse files

nfsd: Fix another OPEN stateid race 



If nfsd4_process_open2() is initialising a new stateid, and yet the
call to nfs4_get_vfs_file() fails for some reason, then we must
declare the stateid closed, and unhash it before dropping the mutex.

Right now, we unhash the stateid after dropping the mutex, and without
changing the stateid type, meaning that another OPEN could theoretically
look it up and attempt to use it.

Reported-by: default avatarAndrew W Elble <aweits@rit.edu>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent 15ca08d3

fs/nfsd/nfs4state.c

+13 −15
Original line number Diff line number Diff line
@@ -4502,6 +4502,7 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf 
	struct nfs4_ol_stateid *stp = NULL;

	struct nfs4_delegation *dp = NULL;

	__be32 status;

	bool new_stp = false;



	/*

	 * Lookup file; if found, lookup stateid and check open request,
@@ -4521,11 +4522,19 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf 
			goto out;

	}



	if (!stp) {

		stp = init_open_stateid(fp, open);

		if (!open->op_stp)

			new_stp = true;

	}



	/*

	 * OPEN the file, or upgrade an existing OPEN.

	 * If truncate fails, the OPEN fails.

	 *

	 * stp is already locked.

	 */

	if (stp) {

	if (!new_stp) {

		/* Stateid was found, this is an OPEN upgrade */

		status = nfs4_upgrade_open(rqstp, fp, current_fh, stp, open);

		if (status) {
@@ -4533,22 +4542,11 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf 
			goto out;

		}

	} else {

		/* stp is returned locked. */

		stp = init_open_stateid(fp, open);

		/* See if we lost the race to some other thread */

		if (stp->st_access_bmap != 0) {

			status = nfs4_upgrade_open(rqstp, fp, current_fh,

						stp, open);

			if (status) {

				mutex_unlock(&stp->st_mutex);

				goto out;

			}

			goto upgrade_out;

		}

		status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open);

		if (status) {

			mutex_unlock(&stp->st_mutex);

			stp->st_stid.sc_type = NFS4_CLOSED_STID;

			release_open_stateid(stp);

			mutex_unlock(&stp->st_mutex);

			goto out;

		}
@@ -4557,7 +4555,7 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf 
		if (stp->st_clnt_odstate == open->op_odstate)

			open->op_odstate = NULL;

	}

upgrade_out:



	nfs4_inc_and_copy_stateid(&open->op_stateid, &stp->st_stid);

	mutex_unlock(&stp->st_mutex);

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