summaryrefslogtreecommitdiff
path: root/include/linux/nfs_fs_sb.h
diff options
context:
space:
mode:
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 /include/linux/nfs_fs_sb.h
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 'include/linux/nfs_fs_sb.h')
-rw-r--r--include/linux/nfs_fs_sb.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 74c44665e6d3..efcfe9ded9ea 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -9,6 +9,7 @@
#include <linux/sunrpc/xprt.h>
#include <linux/atomic.h>
+#include <linux/refcount.h>
struct nfs4_session;
struct nfs_iostats;
@@ -24,7 +25,7 @@ struct nfs41_impl_id;
* The nfs_client identifies our client state to the server.
*/
struct nfs_client {
- atomic_t cl_count;
+ refcount_t cl_count;
atomic_t cl_mds_count;
int cl_cons_state; /* current construction state (-ve: init error) */
#define NFS_CS_READY 0 /* ready to be used */