refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This allows to avoid accidental refcounter overflows that might lead to use-after-free situations.
Signed-off-by: Elena Reshetova <[email protected]> Signed-off-by: Hans Liljestrand <[email protected]> Signed-off-by: Kees Cook <[email protected]> Signed-off-by: David Windsor <[email protected]> --- fs/ceph/caps.c | 4 ++-- fs/ceph/snap.c | 2 +- fs/ceph/super.h | 5 +++-- 3 files changed, 6 insertions(+), 5 deletions(-) diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c index cd966f2..99a77c2c 100644 --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -1389,7 +1389,7 @@ static void __ceph_flush_snaps(struct ceph_inode_info *ci, first_tid = cf->tid + 1; capsnap = container_of(cf, struct ceph_cap_snap, cap_flush); - atomic_inc(&capsnap->nref); + refcount_inc(&capsnap->nref); spin_unlock(&ci->i_ceph_lock); dout("__flush_snaps %p capsnap %p tid %llu %s\n", @@ -2202,7 +2202,7 @@ static void __kick_flushing_caps(struct ceph_mds_client *mdsc, inode, capsnap, cf->tid, ceph_cap_string(capsnap->dirty)); - atomic_inc(&capsnap->nref); + refcount_inc(&capsnap->nref); spin_unlock(&ci->i_ceph_lock); ret = __send_flush_snap(inode, session, capsnap, cap->mseq, diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c index 8f8b41c..dab5d67 100644 --- a/fs/ceph/snap.c +++ b/fs/ceph/snap.c @@ -519,7 +519,7 @@ void ceph_queue_cap_snap(struct ceph_inode_info *ci) capsnap->need_flush ? "" : "no_flush"); ihold(inode); - atomic_set(&capsnap->nref, 1); + refcount_set(&capsnap->nref, 1); INIT_LIST_HEAD(&capsnap->ci_item); capsnap->follows = old_snapc->seq; diff --git a/fs/ceph/super.h b/fs/ceph/super.h index fe6b9cf..c68e6a0 100644 --- a/fs/ceph/super.h +++ b/fs/ceph/super.h @@ -14,6 +14,7 @@ #include <linux/writeback.h> #include <linux/slab.h> #include <linux/posix_acl.h> +#include <linux/refcount.h> #include <linux/ceph/libceph.h> @@ -162,7 +163,7 @@ struct ceph_cap_flush { * data before flushing the snapped state (tracked here) back to the MDS. */ struct ceph_cap_snap { - atomic_t nref; + refcount_t nref; struct list_head ci_item; struct ceph_cap_flush cap_flush; @@ -191,7 +192,7 @@ struct ceph_cap_snap { static inline void ceph_put_cap_snap(struct ceph_cap_snap *capsnap) { - if (atomic_dec_and_test(&capsnap->nref)) { + if (refcount_dec_and_test(&capsnap->nref)) { if (capsnap->xattr_blob) ceph_buffer_put(capsnap->xattr_blob); kfree(capsnap); -- 2.7.4
