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nfsd: Fix another OPEN stateid race

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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>
This commit is contained in:
Trond Myklebust 2017-11-03 08:00:11 -04:00 committed by J. Bruce Fields
parent 15ca08d329
commit d8a1a00055
1 changed files with 13 additions and 15 deletions
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28
fs/nfsd/nfs4state.c
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@ -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);