[PATCH 3.16 049/132] bcache: fix memory corruption in init error path

[Ben Hutchings]

3.16.74-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Slava Pestov <s...@daterainc.com>

commit c9a78332b42cbdcdd386a95192a716b67d1711a4 upstream.

If register_cache_set() failed, we would touch ca->set after
it had already been freed. Also, fix an assertion to catch
this.

Change-Id: I748e5f5b223e2d9b2602075dec2f997cced2394d
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
 drivers/md/bcache/super.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1365,8 +1365,11 @@ static void cache_set_free(struct closur
        bch_journal_free(c);
 
        for_each_cache(ca, c, i)
-               if (ca)
+               if (ca) {
+                       ca->set = NULL;
+                       c->cache[ca->sb.nr_this_dev] = NULL;
                        kobject_put(&ca->kobj);
+               }
 
        bch_bset_sort_state_free(&c->sort);
        free_pages((unsigned long) c->uuids, ilog2(bucket_pages(c)));
@@ -1804,8 +1807,10 @@ void bch_cache_release(struct kobject *k
        struct cache *ca = container_of(kobj, struct cache, kobj);
        unsigned i;
 
-       if (ca->set)
+       if (ca->set) {
+               BUG_ON(ca->set->cache[ca->sb.nr_this_dev] != ca);
                ca->set->cache[ca->sb.nr_this_dev] = NULL;
+       }
 
        bio_split_pool_free(&ca->bio_split_hook);
 
@@ -1868,7 +1873,7 @@ static int cache_alloc(struct cache_sb *
 }
 
 static int register_cache(struct cache_sb *sb, struct page *sb_page,
-                                 struct block_device *bdev, struct cache *ca)
+                               struct block_device *bdev, struct cache *ca)
 {
        char name[BDEVNAME_SIZE];
        const char *err = NULL; /* must be set for any error case */