Re: [PATCH] Btrfs: fix memory leak in btrfs_create_tree()

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Hi Alex,

On 2014/03/28 0:50, Alex Lyakas wrote:
Hi Tsutomu Itoh,

On Thu, Mar 21, 2013 at 6:32 AM, Tsutomu Itoh <t-itoh@xxxxxxxxxxxxxx> wrote:
We should free leaf and root before returning from the error
handling code.

Signed-off-by: Tsutomu Itoh <t-itoh@xxxxxxxxxxxxxx>
---
  fs/btrfs/disk-io.c | 12 +++++++++---
  1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 7d84651..b1b5baa 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1291,6 +1291,7 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
                                       0, objectid, NULL, 0, 0, 0);
         if (IS_ERR(leaf)) {
                 ret = PTR_ERR(leaf);
+               leaf = NULL;
                 goto fail;
         }

@@ -1334,11 +1335,16 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,

         btrfs_tree_unlock(leaf);

+       return root;
+
  fail:
-       if (ret)
-               return ERR_PTR(ret);
+       if (leaf) {
+               btrfs_tree_unlock(leaf);
+               free_extent_buffer(leaf);
I believe this is not enough. Few lines above, another reference on
the root is taken by
root->commit_root = btrfs_root_node(root);

Thank you for pointing this out.

You are right.
Could you re-post your fix by the patch submitting form?

Thanks,
Tsutomu


So I believe the proper fix would be:
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index d9698fd..260af79 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1354,10 +1354,10 @@ struct btrfs_root *btrfs_create_tree(struct
btrfs_trans_handle *trans,
         return root;

  fail:
-       if (leaf) {
+       if (leaf)
                 btrfs_tree_unlock(leaf);
-               free_extent_buffer(leaf);
-       }
+       free_extent_buffer(root->node);
+       free_extent_buffer(root->commit_root);
         kfree(root);

         return ERR_PTR(ret);



Thanks,
Alex.



+       }
+       kfree(root);

-       return root;
+       return ERR_PTR(ret);
  }

  static struct btrfs_root *alloc_log_tree(struct btrfs_trans_handle *trans,



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