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authorElena Reshetova <elena.reshetova@intel.com>2017-10-20 12:53:36 +0300
committerAnna Schumaker <Anna.Schumaker@Netapp.com>2017-11-17 21:48:00 +0300
commit194bc1f48100a3b6fbd50d7a2218b594f0c564b6 (patch)
tree0cf26732583370c6ce2dd0b2bf7506ca90ed10b9 /fs/nfs/nfs4_fs.h
parent0896cade1224f167296c786043e9bdc0ca63d392 (diff)
downloadlinux-194bc1f48100a3b6fbd50d7a2218b594f0c564b6.tar.xz
fs, nfs: convert nfs4_lock_state.ls_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_lock_state.ls_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/nfs4_fs.h')
-rw-r--r--fs/nfs/nfs4_fs.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index b547d935aaf0..78946c6ead88 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -144,7 +144,7 @@ struct nfs4_lock_state {
unsigned long ls_flags;
struct nfs_seqid_counter ls_seqid;
nfs4_stateid ls_stateid;
- atomic_t ls_count;
+ refcount_t ls_count;
fl_owner_t ls_owner;
};