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authorElena Reshetova <elena.reshetova@intel.com>2017-10-20 12:53:38 +0300
committerAnna Schumaker <Anna.Schumaker@Netapp.com>2017-11-17 21:48:01 +0300
commit212bf41d88c06afc23e03f9b274eebf1e8dba197 (patch)
tree755a58e9b423e6e8bfe06fa2036b633a427ff42b /fs/nfs/filelayout
parent2f62b5aa4814be2c511553fd6afb4d35b6c2503b (diff)
downloadlinux-212bf41d88c06afc23e03f9b274eebf1e8dba197.tar.xz
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.c12
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)