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/btrfs/backref.c | 2 +- fs/btrfs/delayed-ref.c | 8 ++++---- fs/btrfs/delayed-ref.h | 8 +++++--- fs/btrfs/disk-io.c | 2 +- fs/btrfs/extent-tree.c | 6 +++--- 5 files changed, 14 insertions(+), 12 deletions(-) diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c index 7699e16..1163383 100644 --- a/fs/btrfs/backref.c +++ b/fs/btrfs/backref.c @@ -1286,7 +1286,7 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans, head = btrfs_find_delayed_ref_head(delayed_refs, bytenr); if (head) { if (!mutex_trylock(&head->mutex)) { - atomic_inc(&head->node.refs); + refcount_inc(&head->node.refs); spin_unlock(&delayed_refs->lock); btrfs_release_path(path); diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c index 6eb8095..be70d90 100644 --- a/fs/btrfs/delayed-ref.c +++ b/fs/btrfs/delayed-ref.c @@ -164,7 +164,7 @@ int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans, if (mutex_trylock(&head->mutex)) return 0; - atomic_inc(&head->node.refs); + refcount_inc(&head->node.refs); spin_unlock(&delayed_refs->lock); mutex_lock(&head->mutex); @@ -590,7 +590,7 @@ add_delayed_ref_head(struct btrfs_fs_info *fs_info, delayed_refs = &trans->transaction->delayed_refs; /* first set the basic ref node struct up */ - atomic_set(&ref->refs, 1); + refcount_set(&ref->refs, 1); ref->bytenr = bytenr; ref->num_bytes = num_bytes; ref->ref_mod = count_mod; @@ -682,7 +682,7 @@ add_delayed_tree_ref(struct btrfs_fs_info *fs_info, delayed_refs = &trans->transaction->delayed_refs; /* first set the basic ref node struct up */ - atomic_set(&ref->refs, 1); + refcount_set(&ref->refs, 1); ref->bytenr = bytenr; ref->num_bytes = num_bytes; ref->ref_mod = 1; @@ -739,7 +739,7 @@ add_delayed_data_ref(struct btrfs_fs_info *fs_info, seq = atomic64_read(&fs_info->tree_mod_seq); /* first set the basic ref node struct up */ - atomic_set(&ref->refs, 1); + refcount_set(&ref->refs, 1); ref->bytenr = bytenr; ref->num_bytes = num_bytes; ref->ref_mod = 1; diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h index 0e537f9..c0264ff 100644 --- a/fs/btrfs/delayed-ref.h +++ b/fs/btrfs/delayed-ref.h @@ -18,6 +18,8 @@ #ifndef __DELAYED_REF__ #define __DELAYED_REF__ +#include <linux/refcount.h> + /* these are the possible values of struct btrfs_delayed_ref_node->action */ #define BTRFS_ADD_DELAYED_REF 1 /* add one backref to the tree */ #define BTRFS_DROP_DELAYED_REF 2 /* delete one backref from the tree */ @@ -53,7 +55,7 @@ struct btrfs_delayed_ref_node { u64 seq; /* ref count on this data structure */ - atomic_t refs; + refcount_t refs; /* * how many refs is this entry adding or deleting. For @@ -220,8 +222,8 @@ btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op) static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref) { - WARN_ON(atomic_read(&ref->refs) == 0); - if (atomic_dec_and_test(&ref->refs)) { + WARN_ON(refcount_read(&ref->refs) == 0); + if (refcount_dec_and_test(&ref->refs)) { WARN_ON(ref->in_tree); switch (ref->type) { case BTRFS_TREE_BLOCK_REF_KEY: diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index dca6432..913df60 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -4343,7 +4343,7 @@ static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans, head = rb_entry(node, struct btrfs_delayed_ref_head, href_node); if (!mutex_trylock(&head->mutex)) { - atomic_inc(&head->node.refs); + refcount_inc(&head->node.refs); spin_unlock(&delayed_refs->lock); mutex_lock(&head->mutex); diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 796001b..11a1b07 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -891,7 +891,7 @@ int btrfs_lookup_extent_info(struct btrfs_trans_handle *trans, head = btrfs_find_delayed_ref_head(delayed_refs, bytenr); if (head) { if (!mutex_trylock(&head->mutex)) { - atomic_inc(&head->node.refs); + refcount_inc(&head->node.refs); spin_unlock(&delayed_refs->lock); btrfs_release_path(path); @@ -2979,7 +2979,7 @@ int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans, struct btrfs_delayed_ref_node *ref; ref = &head->node; - atomic_inc(&ref->refs); + refcount_inc(&ref->refs); spin_unlock(&delayed_refs->lock); /* @@ -3056,7 +3056,7 @@ static noinline int check_delayed_ref(struct btrfs_root *root, } if (!mutex_trylock(&head->mutex)) { - atomic_inc(&head->node.refs); + refcount_inc(&head->node.refs); spin_unlock(&delayed_refs->lock); btrfs_release_path(path); -- 2.7.4
