This is a note to let you know that I've just added the patch titled
nfsd: Fix another OPEN stateid race
to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: nfsd-fix-another-open-stateid-race.patch and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
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: nfsd: Fix another OPEN stateid race
From: Trond Myklebust trond.myklebust@primarydata.com
commit d8a1a000555ecd1b824ac1ed6df8fe364dfbbbb0 upstream.
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 Signed-off-by: J. Bruce Fields bfields@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/nfsd/nfs4state.c | 28 +++++++++++++--------------- 1 file changed, 13 insertions(+), 15 deletions(-)
--- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -4319,6 +4319,7 @@ nfsd4_process_open2(struct svc_rqst *rqs 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, @@ -4338,11 +4339,19 @@ nfsd4_process_open2(struct svc_rqst *rqs 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) { @@ -4350,22 +4359,11 @@ nfsd4_process_open2(struct svc_rqst *rqs 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; }
@@ -4374,7 +4372,7 @@ nfsd4_process_open2(struct svc_rqst *rqs 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);
Patches currently in stable-queue which might be from trond.myklebust@primarydata.com are
queue-4.4/nfsd-fix-stateid-races-between-open-and-close.patch queue-4.4/nfsd-fix-another-open-stateid-race.patch