linux/fs/nfs/filelayout
Elena Reshetova 212bf41d88 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>
2017-11-17 13:48:01 -05:00
..
filelayout.c fs, nfs: convert nfs_client.cl_count from atomic_t to refcount_t 2017-11-17 13:48:01 -05:00
filelayout.h NFS store nfs4_deviceid in struct nfs4_filelayout_segment 2017-03-28 11:21:52 -04:00
filelayoutdev.c pNFS/flexfiles: never nfs4_mark_deviceid_unavailable 2017-03-17 16:07:17 -04:00
Makefile Push the file layout driver into a subdirectory 2014-05-29 20:21:56 -04:00