diff options
| author | Elena Reshetova <elena.reshetova@intel.com> | 2017-10-20 12:53:38 +0300 |
|---|---|---|
| committer | Anna Schumaker <Anna.Schumaker@Netapp.com> | 2017-11-17 13:48:01 -0500 |
| commit | 212bf41d88c06afc23e03f9b274eebf1e8dba197 (patch) | |
| tree | 755a58e9b423e6e8bfe06fa2036b633a427ff42b /fs/nfs/filelayout | |
| parent | 2f62b5aa4814be2c511553fd6afb4d35b6c2503b (diff) | |
fs, nfs: convert nfs_client.cl_count from atomic_t to refcount_t
atomic_t variables are currently used to implement reference
counters with the following properties:
- counter is initialized to 1 using atomic_set()
- a resource is freed upon counter reaching zero
- once counter reaches zero, its further
increments aren't allowed
- counter schema uses basic atomic operations
(set, inc, inc_not_zero, dec_and_test, etc.)
Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.
The variable nfs_client.cl_count is used as pure reference counter.
Convert it to refcount_t and fix up the operations.
Suggested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'fs/nfs/filelayout')
| -rw-r--r-- | fs/nfs/filelayout/filelayout.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/fs/nfs/filelayout/filelayout.c b/fs/nfs/filelayout/filelayout.c index 508126eb49f9..4e54d8b5413a 100644 --- a/fs/nfs/filelayout/filelayout.c +++ b/fs/nfs/filelayout/filelayout.c @@ -471,10 +471,10 @@ filelayout_read_pagelist(struct nfs_pgio_header *hdr) return PNFS_NOT_ATTEMPTED; dprintk("%s USE DS: %s cl_count %d\n", __func__, - ds->ds_remotestr, atomic_read(&ds->ds_clp->cl_count)); + ds->ds_remotestr, refcount_read(&ds->ds_clp->cl_count)); /* No multipath support. Use first DS */ - atomic_inc(&ds->ds_clp->cl_count); + refcount_inc(&ds->ds_clp->cl_count); hdr->ds_clp = ds->ds_clp; hdr->ds_commit_idx = idx; fh = nfs4_fl_select_ds_fh(lseg, j); @@ -515,10 +515,10 @@ filelayout_write_pagelist(struct nfs_pgio_header *hdr, int sync) dprintk("%s ino %lu sync %d req %zu@%llu DS: %s cl_count %d\n", __func__, hdr->inode->i_ino, sync, (size_t) hdr->args.count, - offset, ds->ds_remotestr, atomic_read(&ds->ds_clp->cl_count)); + offset, ds->ds_remotestr, refcount_read(&ds->ds_clp->cl_count)); hdr->pgio_done_cb = filelayout_write_done_cb; - atomic_inc(&ds->ds_clp->cl_count); + refcount_inc(&ds->ds_clp->cl_count); hdr->ds_clp = ds->ds_clp; hdr->ds_commit_idx = idx; fh = nfs4_fl_select_ds_fh(lseg, j); @@ -1064,9 +1064,9 @@ static int filelayout_initiate_commit(struct nfs_commit_data *data, int how) goto out_err; dprintk("%s ino %lu, how %d cl_count %d\n", __func__, - data->inode->i_ino, how, atomic_read(&ds->ds_clp->cl_count)); + data->inode->i_ino, how, refcount_read(&ds->ds_clp->cl_count)); data->commit_done_cb = filelayout_commit_done_cb; - atomic_inc(&ds->ds_clp->cl_count); + refcount_inc(&ds->ds_clp->cl_count); data->ds_clp = ds->ds_clp; fh = select_ds_fh_from_commit(lseg, data->ds_commit_index); if (fh) |