diff options
| author | Elena Reshetova <elena.reshetova@intel.com> | 2017-10-20 12:53:38 +0300 |
|---|---|---|
| committer | Anna Schumaker <Anna.Schumaker@Netapp.com> | 2017-11-17 13:48:01 -0500 |
| commit | 212bf41d88c06afc23e03f9b274eebf1e8dba197 (patch) | |
| tree | 755a58e9b423e6e8bfe06fa2036b633a427ff42b /fs/nfs/nfs4state.c | |
| parent | 2f62b5aa4814be2c511553fd6afb4d35b6c2503b (diff) | |
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/nfs4state.c')
| -rw-r--r-- | fs/nfs/nfs4state.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c index 1887134d5231..3bd79b8c016b 100644 --- a/fs/nfs/nfs4state.c +++ b/fs/nfs/nfs4state.c @@ -1177,7 +1177,7 @@ void nfs4_schedule_state_manager(struct nfs_client *clp) if (test_and_set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state) != 0) return; __module_get(THIS_MODULE); - atomic_inc(&clp->cl_count); + refcount_inc(&clp->cl_count); /* The rcu_read_lock() is not strictly necessary, as the state * manager is the only thread that ever changes the rpc_xprt @@ -1269,7 +1269,7 @@ int nfs4_wait_clnt_recover(struct nfs_client *clp) might_sleep(); - atomic_inc(&clp->cl_count); + refcount_inc(&clp->cl_count); res = wait_on_bit_action(&clp->cl_state, NFS4CLNT_MANAGER_RUNNING, nfs_wait_bit_killable, TASK_KILLABLE); if (res) @@ -2510,7 +2510,7 @@ static void nfs4_state_manager(struct nfs_client *clp) break; if (test_and_set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state) != 0) break; - } while (atomic_read(&clp->cl_count) > 1); + } while (refcount_read(&clp->cl_count) > 1); return; out_error: if (strlen(section)) |