[PATCH 07/29] drivers, md: convert dm_dev_internal.count 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/md/dm-table.c | 6 +++---
 drivers/md/dm.h   | 3 ++-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 3ad16d9..d2e2741 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -416,15 +416,15 @@ int dm_get_device(struct dm_target *ti, const char *path, 
fmode_t mode,
return r;
}
 
-   atomic_set(>count, 0);
+   refcount_set(>count, 1);
list_add(>list, >devices);
 
} else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) {
r = upgrade_mode(dd, mode, t->md);
if (r)
return r;
+   refcount_inc(>count);
}
-   atomic_inc(>count);
 
*result = dd->dm_dev;
return 0;
@@ -478,7 +478,7 @@ void dm_put_device(struct dm_target *ti, struct dm_dev *d)
   dm_device_name(ti->table->md), d->name);
return;
}
-   if (atomic_dec_and_test(>count)) {
+   if (refcount_dec_and_test(>count)) {
dm_put_table_device(ti->table->md, d);
list_del(>list);
kfree(dd);
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index f298b01..63b8142 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -19,6 +19,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include "dm-stats.h"
 
@@ -38,7 +39,7 @@
  */
 struct dm_dev_internal {
struct list_head list;
-   atomic_t count;
+   refcount_t count;
struct dm_dev *dm_dev;
 };
 
-- 
2.7.4

[PATCH 07/29] drivers, md: convert dm_dev_internal.count 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/md/dm-table.c | 6 +++---
 drivers/md/dm.h   | 3 ++-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 3ad16d9..d2e2741 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -416,15 +416,15 @@ int dm_get_device(struct dm_target *ti, const char *path, 
fmode_t mode,
return r;
}
 
-   atomic_set(>count, 0);
+   refcount_set(>count, 1);
list_add(>list, >devices);
 
} else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) {
r = upgrade_mode(dd, mode, t->md);
if (r)
return r;
+   refcount_inc(>count);
}
-   atomic_inc(>count);
 
*result = dd->dm_dev;
return 0;
@@ -478,7 +478,7 @@ void dm_put_device(struct dm_target *ti, struct dm_dev *d)
   dm_device_name(ti->table->md), d->name);
return;
}
-   if (atomic_dec_and_test(>count)) {
+   if (refcount_dec_and_test(>count)) {
dm_put_table_device(ti->table->md, d);
list_del(>list);
kfree(dd);
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index f298b01..63b8142 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -19,6 +19,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include "dm-stats.h"
 
@@ -38,7 +39,7 @@
  */
 struct dm_dev_internal {
struct list_head list;
-   atomic_t count;
+   refcount_t count;
struct dm_dev *dm_dev;
 };
 
-- 
2.7.4