dm btree: fix order of block initialization in btree_split_beneath

commit e4f9d6013820d1eba1432d51dd1c5795759aa77f upstream.

When btree_split_beneath() splits a node to two new children, it will
allocate two blocks: left and right.  If right block's allocation
failed, the left block will be unlocked and marked dirty.  If this
happened, the left block'ss content is zero, because it wasn't
initialized with the btree struct before the attempot to allocate the
right block.  Upon return, when flushing the left block to disk, the
validator will fail when check this block.  Then a BUG_ON is raised.

Fix this by completely initializing the left block before allocating and
initializing the right block.

Fixes: 4dcb8b57df359 ("dm btree: fix leak of bufio-backed block in btree_split_beneath error path")
Cc: stable@vger.kernel.org
Signed-off-by: ZhangXiaoxu <zhangxiaoxu5@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/persistent-data/dm-btree.c b/drivers/md/persistent-data/dm-btree.c
index e4ececd3df004b2222f39e2984229c49ef310e63..386215245dfe27d0df9b1b30fb0482218df5c138 100644 (file)
--- a/drivers/md/persistent-data/dm-btree.c
+++ b/drivers/md/persistent-data/dm-btree.c
@@ -623,39 +623,40 @@ static int btree_split_beneath(struct shadow_spine *s, uint64_t key)
 
        new_parent = shadow_current(s);
 
+       pn = dm_block_data(new_parent);
+       size = le32_to_cpu(pn->header.flags) & INTERNAL_NODE ?
+               sizeof(__le64) : s->info->value_type.size;
+
+       /* create & init the left block */
        r = new_block(s->info, &left);
        if (r < 0)
                return r;
 
+       ln = dm_block_data(left);
+       nr_left = le32_to_cpu(pn->header.nr_entries) / 2;
+
+       ln->header.flags = pn->header.flags;
+       ln->header.nr_entries = cpu_to_le32(nr_left);
+       ln->header.max_entries = pn->header.max_entries;
+       ln->header.value_size = pn->header.value_size;
+       memcpy(ln->keys, pn->keys, nr_left * sizeof(pn->keys[0]));
+       memcpy(value_ptr(ln, 0), value_ptr(pn, 0), nr_left * size);
+
+       /* create & init the right block */
        r = new_block(s->info, &right);
        if (r < 0) {
                unlock_block(s->info, left);
                return r;
        }
 
-       pn = dm_block_data(new_parent);
-       ln = dm_block_data(left);
        rn = dm_block_data(right);
-
-       nr_left = le32_to_cpu(pn->header.nr_entries) / 2;
        nr_right = le32_to_cpu(pn->header.nr_entries) - nr_left;
 
-       ln->header.flags = pn->header.flags;
-       ln->header.nr_entries = cpu_to_le32(nr_left);
-       ln->header.max_entries = pn->header.max_entries;
-       ln->header.value_size = pn->header.value_size;
-
        rn->header.flags = pn->header.flags;
        rn->header.nr_entries = cpu_to_le32(nr_right);
        rn->header.max_entries = pn->header.max_entries;
        rn->header.value_size = pn->header.value_size;
-
-       memcpy(ln->keys, pn->keys, nr_left * sizeof(pn->keys[0]));
        memcpy(rn->keys, pn->keys + nr_left, nr_right * sizeof(pn->keys[0]));
-
-       size = le32_to_cpu(pn->header.flags) & INTERNAL_NODE ?
-               sizeof(__le64) : s->info->value_type.size;
-       memcpy(value_ptr(ln, 0), value_ptr(pn, 0), nr_left * size);
        memcpy(value_ptr(rn, 0), value_ptr(pn, nr_left),
               nr_right * size);