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.reshet...@intel.com> Signed-off-by: Hans Liljestrand <ishkam...@gmail.com> Signed-off-by: Kees Cook <keesc...@chromium.org> Signed-off-by: David Windsor <dwind...@gmail.com> --- drivers/md/dm-cache-metadata.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c index e4c2c1a..6d26e71 100644 --- a/drivers/md/dm-cache-metadata.c +++ b/drivers/md/dm-cache-metadata.c @@ -13,6 +13,7 @@ #include "persistent-data/dm-transaction-manager.h" #include <linux/device-mapper.h> +#include <linux/refcount.h> /*----------------------------------------------------------------*/ @@ -102,7 +103,7 @@ struct cache_disk_superblock { } __packed; struct dm_cache_metadata { - atomic_t ref_count; + refcount_t ref_count; struct list_head list; unsigned version; @@ -756,7 +757,7 @@ static struct dm_cache_metadata *metadata_open(struct block_device *bdev, } cmd->version = metadata_version; - atomic_set(&cmd->ref_count, 1); + refcount_set(&cmd->ref_count, 1); init_rwsem(&cmd->root_lock); cmd->bdev = bdev; cmd->data_block_size = data_block_size; @@ -794,7 +795,7 @@ static struct dm_cache_metadata *lookup(struct block_device *bdev) list_for_each_entry(cmd, &table, list) if (cmd->bdev == bdev) { - atomic_inc(&cmd->ref_count); + refcount_inc(&cmd->ref_count); return cmd; } @@ -865,7 +866,7 @@ struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev, void dm_cache_metadata_close(struct dm_cache_metadata *cmd) { - if (atomic_dec_and_test(&cmd->ref_count)) { + if (refcount_dec_and_test(&cmd->ref_count)) { mutex_lock(&table_lock); list_del(&cmd->list); mutex_unlock(&table_lock); -- 2.7.4 _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel