[PATCH 01/29] drivers, block: convert xen_blkif.refcnt from atomic_t to refcount_t

[Elena Reshetova]

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 
---
 drivers/block/xen-blkback/common.h | 7 ---
 drivers/block/xen-blkback/xenbus.c | 2 +-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/block/xen-blkback/common.h 
b/drivers/block/xen-blkback/common.h
index dea61f6..2ccfd62 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -35,6 +35,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
 #include 
@@ -333,7 +334,7 @@ struct xen_blkif {
struct xen_vbd  vbd;
/* Back pointer to the backend_info. */
struct backend_info *be;
-   atomic_trefcnt;
+   refcount_t  refcnt;
/* for barrier (drain) requests */
struct completion   drain_complete;
atomic_tdrain;
@@ -386,10 +387,10 @@ struct pending_req {
 (_v)->bdev->bd_part->nr_sects : \
  get_capacity((_v)->bdev->bd_disk))
 
-#define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt))
+#define xen_blkif_get(_b) (refcount_inc(&(_b)->refcnt))
 #define xen_blkif_put(_b)  \
do {\
-   if (atomic_dec_and_test(&(_b)->refcnt)) \
+   if (refcount_dec_and_test(&(_b)->refcnt))   \
schedule_work(&(_b)->free_work);\
} while (0)
 
diff --git a/drivers/block/xen-blkback/xenbus.c 
b/drivers/block/xen-blkback/xenbus.c
index 8fe61b5..9f89be3 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -176,7 +176,7 @@ static struct xen_blkif *xen_blkif_alloc(domid_t domid)
return ERR_PTR(-ENOMEM);
 
blkif->domid = domid;
-   atomic_set(>refcnt, 1);
+   refcount_set(>refcnt, 1);
init_completion(>drain_complete);
INIT_WORK(>free_work, xen_blkif_deferred_free);
 
-- 
2.7.4

[PATCH 01/29] drivers, block: convert xen_blkif.refcnt from atomic_t to refcount_t

[Elena Reshetova]

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 
---
 drivers/block/xen-blkback/common.h | 7 ---
 drivers/block/xen-blkback/xenbus.c | 2 +-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/block/xen-blkback/common.h 
b/drivers/block/xen-blkback/common.h
index dea61f6..2ccfd62 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -35,6 +35,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
 #include 
@@ -333,7 +334,7 @@ struct xen_blkif {
struct xen_vbd  vbd;
/* Back pointer to the backend_info. */
struct backend_info *be;
-   atomic_trefcnt;
+   refcount_t  refcnt;
/* for barrier (drain) requests */
struct completion   drain_complete;
atomic_tdrain;
@@ -386,10 +387,10 @@ struct pending_req {
 (_v)->bdev->bd_part->nr_sects : \
  get_capacity((_v)->bdev->bd_disk))
 
-#define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt))
+#define xen_blkif_get(_b) (refcount_inc(&(_b)->refcnt))
 #define xen_blkif_put(_b)  \
do {\
-   if (atomic_dec_and_test(&(_b)->refcnt)) \
+   if (refcount_dec_and_test(&(_b)->refcnt))   \
schedule_work(&(_b)->free_work);\
} while (0)
 
diff --git a/drivers/block/xen-blkback/xenbus.c 
b/drivers/block/xen-blkback/xenbus.c
index 8fe61b5..9f89be3 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -176,7 +176,7 @@ static struct xen_blkif *xen_blkif_alloc(domid_t domid)
return ERR_PTR(-ENOMEM);
 
blkif->domid = domid;
-   atomic_set(>refcnt, 1);
+   refcount_set(>refcnt, 1);
init_completion(>drain_complete);
INIT_WORK(>free_work, xen_blkif_deferred_free);
 
-- 
2.7.4