On Tue, Feb 21, 2017 at 05:49:01PM +0200, Elena Reshetova wrote:
> 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@xxxxxxxxx>
> Signed-off-by: Hans Liljestrand <ishkamiel@xxxxxxxxx>
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> Signed-off-by: David Windsor <dwindsor@xxxxxxxxx>
> ---
> 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>
Seeing as you're sprinkling refcount_t all over XFS, this ought to go in
xfs_linux.h with all the other Linux-specific #includes.
--D
> +
> /*
> * 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
>
> --
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