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Commit dec95574 authored by Elena Reshetova's avatar Elena Reshetova Committed by David Sterba
Browse files

btrfs: convert btrfs_raid_bio.refs from atomic_t to refcount_t 



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: default avatarElena Reshetova <elena.reshetova@intel.com>
Signed-off-by: default avatarHans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarDavid Windsor <dwindsor@gmail.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 99f4cdb1

fs/btrfs/raid56.c

+9 −10
Original line number Diff line number Diff line
@@ -149,7 +149,7 @@ struct btrfs_raid_bio { 


	int generic_bio_cnt;



	atomic_t refs;

	refcount_t refs;



	atomic_t stripes_pending;
@@ -389,7 +389,7 @@ static void __remove_rbio_from_cache(struct btrfs_raid_bio *rbio) 
		if (bio_list_empty(&rbio->bio_list)) {

			if (!list_empty(&rbio->hash_list)) {

				list_del_init(&rbio->hash_list);

				atomic_dec(&rbio->refs);

				refcount_dec(&rbio->refs);

				BUG_ON(!list_empty(&rbio->plug_list));

			}

		}
@@ -480,7 +480,7 @@ static void cache_rbio(struct btrfs_raid_bio *rbio) 


	/* bump our ref if we were not in the list before */

	if (!test_and_set_bit(RBIO_CACHE_BIT, &rbio->flags))

		atomic_inc(&rbio->refs);

		refcount_inc(&rbio->refs);



	if (!list_empty(&rbio->stripe_cache)){

		list_move(&rbio->stripe_cache, &table->stripe_cache);
@@ -689,7 +689,7 @@ static noinline int lock_stripe_add(struct btrfs_raid_bio *rbio) 
			    test_bit(RBIO_CACHE_BIT, &cur->flags) &&

			    !test_bit(RBIO_RMW_LOCKED_BIT, &cur->flags)) {

				list_del_init(&cur->hash_list);

				atomic_dec(&cur->refs);

				refcount_dec(&cur->refs);



				steal_rbio(cur, rbio);

				cache_drop = cur;
@@ -738,7 +738,7 @@ static noinline int lock_stripe_add(struct btrfs_raid_bio *rbio) 
		}

	}

lockit:

	atomic_inc(&rbio->refs);

	refcount_inc(&rbio->refs);

	list_add(&rbio->hash_list, &h->hash_list);

out:

	spin_unlock_irqrestore(&h->lock, flags);
@@ -784,7 +784,7 @@ static noinline void unlock_stripe(struct btrfs_raid_bio *rbio) 
		}



		list_del_init(&rbio->hash_list);

		atomic_dec(&rbio->refs);

		refcount_dec(&rbio->refs);



		/*

		 * we use the plug list to hold all the rbios
@@ -801,7 +801,7 @@ static noinline void unlock_stripe(struct btrfs_raid_bio *rbio) 
			list_del_init(&rbio->plug_list);



			list_add(&next->hash_list, &h->hash_list);

			atomic_inc(&next->refs);

			refcount_inc(&next->refs);

			spin_unlock(&rbio->bio_list_lock);

			spin_unlock_irqrestore(&h->lock, flags);
@@ -843,8 +843,7 @@ static void __free_raid_bio(struct btrfs_raid_bio *rbio) 
{

	int i;



	WARN_ON(atomic_read(&rbio->refs) < 0);

	if (!atomic_dec_and_test(&rbio->refs))

	if (!refcount_dec_and_test(&rbio->refs))

		return;



	WARN_ON(!list_empty(&rbio->stripe_cache));
@@ -997,7 +996,7 @@ static struct btrfs_raid_bio *alloc_rbio(struct btrfs_fs_info *fs_info, 
	rbio->stripe_npages = stripe_npages;

	rbio->faila = -1;

	rbio->failb = -1;

	atomic_set(&rbio->refs, 1);

	refcount_set(&rbio->refs, 1);

	atomic_set(&rbio->error, 0);

	atomic_set(&rbio->stripes_pending, 0);