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>
---
 fs/xfs/xfs_extfree_item.c | 4 ++--
 fs/xfs/xfs_extfree_item.h | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/xfs_extfree_item.c b/fs/xfs/xfs_extfree_item.c
index d7bc149..4e0acf0 100644
--- a/fs/xfs/xfs_extfree_item.c
+++ b/fs/xfs/xfs_extfree_item.c
@@ -220,7 +220,7 @@ xfs_efi_init(
        efip->efi_format.efi_nextents = nextents;
        efip->efi_format.efi_id = (uintptr_t)(void *)efip;
        atomic_set(&efip->efi_next_extent, 0);
-       atomic_set(&efip->efi_refcount, 2);
+       refcount_set(&efip->efi_refcount, 2);
 
        return efip;
 }
@@ -290,7 +290,7 @@ void
 xfs_efi_release(
        struct xfs_efi_log_item *efip)
 {
-       if (atomic_dec_and_test(&efip->efi_refcount)) {
+       if (refcount_dec_and_test(&efip->efi_refcount)) {
                xfs_trans_ail_remove(&efip->efi_item, SHUTDOWN_LOG_IO_ERROR);
                xfs_efi_item_free(efip);
        }
diff --git a/fs/xfs/xfs_extfree_item.h b/fs/xfs/xfs_extfree_item.h
index a32c794..fadf736 100644
--- a/fs/xfs/xfs_extfree_item.h
+++ b/fs/xfs/xfs_extfree_item.h
@@ -64,7 +64,7 @@ struct kmem_zone;
  */
 typedef struct xfs_efi_log_item {
        xfs_log_item_t          efi_item;
-       atomic_t                efi_refcount;
+       refcount_t              efi_refcount;
        atomic_t                efi_next_extent;
        unsigned long           efi_flags;      /* misc flags */
        xfs_efi_log_format_t    efi_format;
-- 
2.7.4

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