gregkh@linuxfoundation.org writes:

The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

Greg,

These backport cleanly if you cherry-pick 8c7245abda first:

commit 8c7245abda877d4689b3371db8ae2a4400d7d9ce then commit 15ca08d3299682dc49bad73251677b2c5017ef08 then commit d8a1a000555ecd1b824ac1ed6df8fe364dfbbbb0

Thanks,

Andy

------------------ original commit in Linus's tree ------------------

...

From d8a1a000555ecd1b824ac1ed6df8fe364dfbbbb0 Mon Sep 17 00:00:00 2001

From: Trond Myklebust trond.myklebust@primarydata.com Date: Fri, 3 Nov 2017 08:00:11 -0400 Subject: [PATCH] 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: Andrew W Elble aweits@rit.edu Signed-off-by: Trond Myklebust trond.myklebust@primarydata.com Cc: stable@vger.kernel.org Signed-off-by: J. Bruce Fields bfields@redhat.com

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index ee8fde2dfa92..457f0e7ece74 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -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);