diff options
author | Elena Reshetova <elena.reshetova@intel.com> | 2017-10-20 12:53:31 +0300 |
---|---|---|
committer | Anna Schumaker <Anna.Schumaker@Netapp.com> | 2017-11-17 13:47:59 -0500 |
commit | a2a5dea7b6cb77365ed9c987f54d160668c8a95f (patch) | |
tree | 97c432cfc80701b303d2708e42dbd3df05b9b376 /fs | |
parent | 3be0f80b5fe9c16eca2d538f799b94ca8aa59433 (diff) | |
download | linux-a2a5dea7b6cb77365ed9c987f54d160668c8a95f.tar.bz2 |
fs, nfs: convert nfs4_pnfs_ds.ds_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 nfs4_pnfs_ds.ds_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')
-rw-r--r-- | fs/nfs/pnfs.h | 3 | ||||
-rw-r--r-- | fs/nfs/pnfs_nfs.c | 10 |
2 files changed, 7 insertions, 6 deletions
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h index 87f144f14d1e..cefa7daf6e85 100644 --- a/fs/nfs/pnfs.h +++ b/fs/nfs/pnfs.h @@ -30,6 +30,7 @@ #ifndef FS_NFS_PNFS_H #define FS_NFS_PNFS_H +#include <linux/refcount.h> #include <linux/nfs_fs.h> #include <linux/nfs_page.h> #include <linux/workqueue.h> @@ -54,7 +55,7 @@ struct nfs4_pnfs_ds { char *ds_remotestr; /* comma sep list of addrs */ struct list_head ds_addrs; struct nfs_client *ds_clp; - atomic_t ds_count; + refcount_t ds_count; unsigned long ds_state; #define NFS4DS_CONNECTING 0 /* ds is establishing connection */ }; diff --git a/fs/nfs/pnfs_nfs.c b/fs/nfs/pnfs_nfs.c index 60da59be83b6..03aaa60c7768 100644 --- a/fs/nfs/pnfs_nfs.c +++ b/fs/nfs/pnfs_nfs.c @@ -338,7 +338,7 @@ print_ds(struct nfs4_pnfs_ds *ds) " client %p\n" " cl_exchange_flags %x\n", ds->ds_remotestr, - atomic_read(&ds->ds_count), ds->ds_clp, + refcount_read(&ds->ds_count), ds->ds_clp, ds->ds_clp ? ds->ds_clp->cl_exchange_flags : 0); } @@ -451,7 +451,7 @@ static void destroy_ds(struct nfs4_pnfs_ds *ds) void nfs4_pnfs_ds_put(struct nfs4_pnfs_ds *ds) { - if (atomic_dec_and_lock(&ds->ds_count, + if (refcount_dec_and_lock(&ds->ds_count, &nfs4_ds_cache_lock)) { list_del_init(&ds->ds_node); spin_unlock(&nfs4_ds_cache_lock); @@ -537,7 +537,7 @@ nfs4_pnfs_ds_add(struct list_head *dsaddrs, gfp_t gfp_flags) INIT_LIST_HEAD(&ds->ds_addrs); list_splice_init(dsaddrs, &ds->ds_addrs); ds->ds_remotestr = remotestr; - atomic_set(&ds->ds_count, 1); + refcount_set(&ds->ds_count, 1); INIT_LIST_HEAD(&ds->ds_node); ds->ds_clp = NULL; list_add(&ds->ds_node, &nfs4_data_server_cache); @@ -546,10 +546,10 @@ nfs4_pnfs_ds_add(struct list_head *dsaddrs, gfp_t gfp_flags) } else { kfree(remotestr); kfree(ds); - atomic_inc(&tmp_ds->ds_count); + refcount_inc(&tmp_ds->ds_count); dprintk("%s data server %s found, inc'ed ds_count to %d\n", __func__, tmp_ds->ds_remotestr, - atomic_read(&tmp_ds->ds_count)); + refcount_read(&tmp_ds->ds_count)); ds = tmp_ds; } spin_unlock(&nfs4_ds_cache_lock); |