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authorElena Reshetova <elena.reshetova@intel.com>2017-10-31 00:46:32 +0300
committerJens Axboe <axboe@kernel.dk>2017-10-31 00:57:54 +0300
commit3b304d24a718ae779ee9c7f2014dd3b2d0893b70 (patch)
tree6357ed6aa6ed01c1f81156e8ab9c29c289b85634 /drivers/md/bcache/writeback.h
parentd59b23795933678c9638fd20c942d2b4f3cd6185 (diff)
downloadlinux-3b304d24a718ae779ee9c7f2014dd3b2d0893b70.tar.xz
bcache: convert cached_dev.count from atomic_t to refcount_t
atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable cached_dev.count is used as pure reference counter. Convert it to refcount_t and fix up the operations. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Reviewed-by: Michael Lyle <mlyle@lyle.org> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/md/bcache/writeback.h')
-rw-r--r--drivers/md/bcache/writeback.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/md/bcache/writeback.h b/drivers/md/bcache/writeback.h
index 34bcf49d737b..7d25bff37a9b 100644
--- a/drivers/md/bcache/writeback.h
+++ b/drivers/md/bcache/writeback.h
@@ -91,7 +91,7 @@ static inline void bch_writeback_add(struct cached_dev *dc)
{
if (!atomic_read(&dc->has_dirty) &&
!atomic_xchg(&dc->has_dirty, 1)) {
- atomic_inc(&dc->count);
+ refcount_inc(&dc->count);
if (BDEV_STATE(&dc->sb) != BDEV_STATE_DIRTY) {
SET_BDEV_STATE(&dc->sb, BDEV_STATE_DIRTY);