diff options
| author | Elena Reshetova <elena.reshetova@intel.com> | 2017-10-20 12:53:30 +0300 |
|---|---|---|
| committer | J. Bruce Fields <bfields@redhat.com> | 2017-11-07 16:43:59 -0500 |
| commit | 818a34eb266449b1c89242596039a5e44c9be04c (patch) | |
| tree | 7c9affb6d729a990155f33db99d6e31090aa88d6 /fs | |
| parent | cff7cb2ece397760195ff8a5fc6bf3c860810246 (diff) | |
fs, nfsd: convert nfs4_file.fi_ref 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_file.fi_ref 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: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/nfsd/nfs4state.c | 6 | ||||
| -rw-r--r-- | fs/nfsd/state.h | 4 |
2 files changed, 5 insertions, 5 deletions
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 3f10a397e5ba..e905bf642a53 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -359,7 +359,7 @@ put_nfs4_file(struct nfs4_file *fi) { might_lock(&state_lock); - if (atomic_dec_and_lock(&fi->fi_ref, &state_lock)) { + if (refcount_dec_and_lock(&fi->fi_ref, &state_lock)) { hlist_del_rcu(&fi->fi_hash); spin_unlock(&state_lock); WARN_ON_ONCE(!list_empty(&fi->fi_clnt_odstate)); @@ -3401,7 +3401,7 @@ static void nfsd4_init_file(struct knfsd_fh *fh, unsigned int hashval, { lockdep_assert_held(&state_lock); - atomic_set(&fp->fi_ref, 1); + refcount_set(&fp->fi_ref, 1); spin_lock_init(&fp->fi_lock); INIT_LIST_HEAD(&fp->fi_stateids); INIT_LIST_HEAD(&fp->fi_delegations); @@ -3697,7 +3697,7 @@ find_file_locked(struct knfsd_fh *fh, unsigned int hashval) hlist_for_each_entry_rcu(fp, &file_hashtbl[hashval], fi_hash) { if (fh_match(&fp->fi_fhandle, fh)) { - if (atomic_inc_not_zero(&fp->fi_ref)) + if (refcount_inc_not_zero(&fp->fi_ref)) return fp; } } diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h index 2ed368a91a10..f3772ea8ba0d 100644 --- a/fs/nfsd/state.h +++ b/fs/nfsd/state.h @@ -484,7 +484,7 @@ struct nfs4_clnt_odstate { * the global state_lock spinlock. */ struct nfs4_file { - atomic_t fi_ref; + refcount_t fi_ref; spinlock_t fi_lock; struct hlist_node fi_hash; /* hash on fi_fhandle */ struct list_head fi_stateids; @@ -637,7 +637,7 @@ struct nfs4_file *find_file(struct knfsd_fh *fh); void put_nfs4_file(struct nfs4_file *fi); static inline void get_nfs4_file(struct nfs4_file *fi) { - atomic_inc(&fi->fi_ref); + refcount_inc(&fi->fi_ref); } struct file *find_any_file(struct nfs4_file *f); |