[PATCH 07/29] drivers, md: convert dm_dev_internal.count from atomic_t to refcount_t
From: Elena Reshetova <elena.reshetova@intel.com>
Date: 2017-03-06 14:35:20
Also in:
linux-bcache, linux-media, linux-pci, linux-s390, linux-scsi, linux-serial, lkml, netdev
Subsystem:
device-mapper (lvm), the rest · Maintainers:
Alasdair Kergon, Mike Snitzer, Mikulas Patocka, Benjamin Marzinski, Linus Torvalds
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@intel.com> Signed-off-by: Hans Liljestrand <redacted> Signed-off-by: Kees Cook <redacted> Signed-off-by: David Windsor <redacted> --- 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(&dd->count, 0); + refcount_set(&dd->count, 1); list_add(&dd->list, &t->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(&dd->count); } - atomic_inc(&dd->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(&dd->count)) { + if (refcount_dec_and_test(&dd->count)) { dm_put_table_device(ti->table->md, d); list_del(&dd->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 <linux/hdreg.h> #include <linux/completion.h> #include <linux/kobject.h> +#include <linux/refcount.h> #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