From dec95574f4e6545c701420b950278dc6f55d0368 Mon Sep 17 00:00:00 2001 From: Elena Reshetova Date: Fri, 3 Mar 2017 10:55:26 +0200 Subject: [PATCH] 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: Elena Reshetova Signed-off-by: Hans Liljestrand Signed-off-by: Kees Cook Signed-off-by: David Windsor Signed-off-by: David Sterba --- fs/btrfs/raid56.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c index 1571bf26dc07..a8954f5188b4 100644 --- a/fs/btrfs/raid56.c +++ b/fs/btrfs/raid56.c @@ -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); -- 2.20.1