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/xfs/xfs_bmap_item.c | 4 ++-- fs/xfs/xfs_bmap_item.h | 4 +++- 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/xfs/xfs_bmap_item.c b/fs/xfs/xfs_bmap_item.c index 9bf57c7..33104ad 100644 --- a/fs/xfs/xfs_bmap_item.c +++ b/fs/xfs/xfs_bmap_item.c @@ -199,7 +199,7 @@ xfs_bui_init( buip->bui_format.bui_nextents = XFS_BUI_MAX_FAST_EXTENTS; buip->bui_format.bui_id = (uintptr_t)(void *)buip; atomic_set(&buip->bui_next_extent, 0); - atomic_set(&buip->bui_refcount, 2); + refcount_set(&buip->bui_refcount, 2); return buip; } @@ -215,7 +215,7 @@ void xfs_bui_release( struct xfs_bui_log_item *buip) { - if (atomic_dec_and_test(&buip->bui_refcount)) { + if (refcount_dec_and_test(&buip->bui_refcount)) { xfs_trans_ail_remove(&buip->bui_item, SHUTDOWN_LOG_IO_ERROR); xfs_bui_item_free(buip); } diff --git a/fs/xfs/xfs_bmap_item.h b/fs/xfs/xfs_bmap_item.h index c867daa..988a6ae 100644 --- a/fs/xfs/xfs_bmap_item.h +++ b/fs/xfs/xfs_bmap_item.h @@ -20,6 +20,8 @@ #ifndef __XFS_BMAP_ITEM_H__ #define __XFS_BMAP_ITEM_H__ +#include <linux/refcount.h> + /* * There are (currently) two pairs of bmap btree redo item types: map & unmap. * The common abbreviations for these are BUI (bmap update intent) and BUD @@ -61,7 +63,7 @@ struct kmem_zone; */ struct xfs_bui_log_item { struct xfs_log_item bui_item; - atomic_t bui_refcount; + refcount_t bui_refcount; atomic_t bui_next_extent; unsigned long bui_flags; /* misc flags */ struct xfs_bui_log_format bui_format; -- 2.7.4
