btrfs: convert btrfs_delayed_ref_node.refs from atomic_t to refcount_t

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 <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 7699e16784d313459181c746d0b8c30d468e23a7..116338344224c80c5071421f6833841ca522a7d8 100644 (file)
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -1286,7 +1286,7 @@ again:
                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 6eb80952efb3310ae55de9c2e234319abe14465a..be70d90dfee591953d53100b3c872d0efc5f324f 100644 (file)
--- 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 0e537f98f1a1c63c529c118baed1cac26efa194e..c0264ff01b53cfe9e2fa44a7cdd7e9352012f0ee 100644 (file)
--- 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 e4aa64c263f918232d1553e410273c7a8326b367..3748bc54a6ab7ba57819c120cc1f021c6a798bc6 100644 (file)
--- 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 5c84eea60703fe1239613545c1d197cf618281a3..5a7ddcff406b8d2892af6652bac0be64967782b2 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -892,7 +892,7 @@ search_again:
        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);
@@ -2980,7 +2980,7 @@ again:
                                struct btrfs_delayed_ref_node *ref;
 
                                ref = &head->node;
-                               atomic_inc(&ref->refs);
+                               refcount_inc(&ref->refs);
 
                                spin_unlock(&delayed_refs->lock);
                                /*
@@ -3057,7 +3057,7 @@ 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);