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Date: Fri, 3 Mar 2017 10:55:15 +0200
From: Elena Reshetova <elena.reshetova@...el.com>
To: linux-kernel@...r.kernel.org
Cc: linux-fsdevel@...r.kernel.org, linux-btrfs@...r.kernel.org,
peterz@...radead.org, gregkh@...uxfoundation.org, jbacik@...com,
clm@...com, dsterba@...e.com,
Elena Reshetova <elena.reshetova@...el.com>,
Hans Liljestrand <ishkamiel@...il.com>,
Kees Cook <keescook@...omium.org>,
David Windsor <dwindsor@...il.com>
Subject: [PATCH 06/17] fs, 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@...el.com>
Signed-off-by: Hans Liljestrand <ishkamiel@...il.com>
Signed-off-by: Kees Cook <keescook@...omium.org>
Signed-off-by: David Windsor <dwindsor@...il.com>
---
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
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