From 0700cea7c8b387c8c6bc4de79b197baa0b3fc4a3 Mon Sep 17 00:00:00 2001 From: Elena Reshetova Date: Fri, 3 Mar 2017 10:55:18 +0200 Subject: [PATCH] btrfs: convert btrfs_root.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 Signed-off-by: Hans Liljestrand Signed-off-by: Kees Cook Signed-off-by: David Windsor Signed-off-by: David Sterba --- fs/btrfs/ctree.h | 2 +- fs/btrfs/disk-io.c | 2 +- fs/btrfs/disk-io.h | 4 ++-- 3 files changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index cdfc2a4..285566c 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1222,7 +1222,7 @@ struct btrfs_root { dev_t anon_dev; spinlock_t root_item_lock; - atomic_t refs; + refcount_t refs; struct mutex delalloc_mutex; spinlock_t delalloc_lock; diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 3748bc54..bd415e1 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1340,7 +1340,7 @@ static void __setup_root(struct btrfs_root *root, struct btrfs_fs_info *fs_info, atomic_set(&root->log_writers, 0); atomic_set(&root->log_batch, 0); atomic_set(&root->orphan_inodes, 0); - atomic_set(&root->refs, 1); + refcount_set(&root->refs, 1); atomic_set(&root->will_be_snapshoted, 0); atomic64_set(&root->qgroup_meta_rsv, 0); root->log_transid = 0; diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h index 2e0ec29..21f1ceb 100644 --- a/fs/btrfs/disk-io.h +++ b/fs/btrfs/disk-io.h @@ -101,14 +101,14 @@ struct btrfs_root *btrfs_alloc_dummy_root(struct btrfs_fs_info *fs_info); */ static inline struct btrfs_root *btrfs_grab_fs_root(struct btrfs_root *root) { - if (atomic_inc_not_zero(&root->refs)) + if (refcount_inc_not_zero(&root->refs)) return root; return NULL; } static inline void btrfs_put_fs_root(struct btrfs_root *root) { - if (atomic_dec_and_test(&root->refs)) + if (refcount_dec_and_test(&root->refs)) kfree(root); } -- 2.7.4