diff options
| author | Mike Snitzer <snitzer@kernel.org> | 2024-10-03 15:34:58 -0400 |
|---|---|---|
| committer | Anna Schumaker <anna.schumaker@oracle.com> | 2024-10-03 16:19:43 -0400 |
| commit | 65f2a5c366353da6fa724c68347e1de954928143 (patch) | |
| tree | 3dbc942931e5b9c55c54519e9fcf846b841cd8be /fs/nfs_common | |
| parent | a848c29e3486189aaabd5663bc11aea50c5bd144 (diff) | |
nfs_common: fix race in NFS calls to nfsd_file_put_local() and nfsd_serv_put()
Add nfs_to_nfsd_file_put_local() interface to fix race with nfsd
module unload. Similarly, use RCU around nfs_open_local_fh()'s error
path call to nfs_to->nfsd_serv_put(). Holding RCU ensures that NFS
will safely _call and return_ from its nfs_to calls into the NFSD
functions nfsd_file_put_local() and nfsd_serv_put().
Otherwise, if RCU isn't used then there is a narrow window when NFS's
reference for the nfsd_file and nfsd_serv are dropped and the NFSD
module could be unloaded, which could result in a crash from the
return instruction for either nfs_to->nfsd_file_put_local() or
nfs_to->nfsd_serv_put().
Reported-by: NeilBrown <neilb@suse.de>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
Diffstat (limited to 'fs/nfs_common')
| -rw-r--r-- | fs/nfs_common/nfslocalio.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/fs/nfs_common/nfslocalio.c b/fs/nfs_common/nfslocalio.c index 42b479b9191f..5c8ce5066c16 100644 --- a/fs/nfs_common/nfslocalio.c +++ b/fs/nfs_common/nfslocalio.c @@ -142,8 +142,11 @@ struct nfsd_file *nfs_open_local_fh(nfs_uuid_t *uuid, /* We have an implied reference to net thanks to nfsd_serv_try_get */ localio = nfs_to->nfsd_open_local_fh(net, uuid->dom, rpc_clnt, cred, nfs_fh, fmode); - if (IS_ERR(localio)) + if (IS_ERR(localio)) { + rcu_read_lock(); nfs_to->nfsd_serv_put(net); + rcu_read_unlock(); + } return localio; } EXPORT_SYMBOL_GPL(nfs_open_local_fh); |