Btrfs: fix use after free when close_ctree frees the orphan_rsv

Near the end of close_ctree, we're calling btrfs_free_block_rsv
to free up the orphan rsv.  The problem is this call updates the
space_info, which has already been freed.

This adds a new __ function that directly calls kfree instead of trying
to update the space infos.

Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 83051fa..10b6a75 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3470,6 +3470,7 @@ struct btrfs_block_rsv *btrfs_alloc_block_rsv(struct btrfs_root *root,
                                              unsigned short type);
 void btrfs_free_block_rsv(struct btrfs_root *root,
                          struct btrfs_block_rsv *rsv);
+void __btrfs_free_block_rsv(struct btrfs_block_rsv *rsv);
 int btrfs_block_rsv_add(struct btrfs_root *root,
                        struct btrfs_block_rsv *block_rsv, u64 num_bytes,
                        enum btrfs_reserve_flush_enum flush);

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index b5e3d5f..62cd3b6 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3766,7 +3766,7 @@ void close_ctree(struct btrfs_root *root)
 
        btrfs_free_stripe_hash_table(fs_info);
 
-       btrfs_free_block_rsv(root, root->orphan_block_rsv);
+       __btrfs_free_block_rsv(root->orphan_block_rsv);
        root->orphan_block_rsv = NULL;
 
        lock_chunks(root);

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 02c2b29..875ba51 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4918,6 +4918,11 @@ void btrfs_free_block_rsv(struct btrfs_root *root,
        kfree(rsv);
 }
 
+void __btrfs_free_block_rsv(struct btrfs_block_rsv *rsv)
+{
+       kfree(rsv);
+}
+
 int btrfs_block_rsv_add(struct btrfs_root *root,
                        struct btrfs_block_rsv *block_rsv, u64 num_bytes,
                        enum btrfs_reserve_flush_enum flush)