Re: [PATCH] ceph: fix memory leak in mount error path when using test_dummy_encryption

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On 07/11/2022 18:23, Luís Henriques wrote:
On Mon, Nov 07, 2022 at 03:47:23PM +0800, Xiubo Li wrote:
On 03/11/2022 23:36, Luís Henriques wrote:
Because ceph_init_fs_context() will never be invoced in case we get a
mount error, destroy_mount_options() won't be releasing fscrypt resources
with fscrypt_free_dummy_policy().  This will result in a memory leak.  Add
an invocation to this function in the mount error path.

Signed-off-by: Luís Henriques <lhenriques@xxxxxxx>
---
   fs/ceph/super.c | 1 +
   1 file changed, 1 insertion(+)

diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index 2224d44d21c0..6b9fd04b25cd 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -1362,6 +1362,7 @@ static int ceph_get_tree(struct fs_context *fc)
   	ceph_mdsc_close_sessions(fsc->mdsc);
   	deactivate_locked_super(sb);
+	fscrypt_free_dummy_policy(&fsc->fsc_dummy_enc_policy);
Hi Luis,

BTW, any reason the following code won't be triggered ?

deactivate_locked_super(sb);

   --> fs->kill_sb(s);

         --> ceph_kill_sb()

               --> kill_anon_super()

                     --> generic_shutdown_super()

                           --> sop->put_super()

                                 --> ceph_put_super()

                                       --> ceph_fscrypt_free_dummy_policy()

                                            --> fscrypt_free_dummy_policy(

Here's what I'm seeing here:

   sys_mount->path_mount->do_new_mount->vfs_get_tree->ceph_get_tree

ceph_get_tree() fails due to ceph_real_mount() returning an error.  My
understanding is that that, since fc->root is never set, that code path
will never be triggered.  Does that make sense?

Okay, you are right!

How about fixing it in ceph_real_mount() instead ?


An easy way to reproduce is by running fstest ceph/005 with the
'test_dummy_encryption' option.  (I'll probably need to send a patch to
disable this test when this option is present.)

Anyway this should be fixed in kceph.

Thanks!

- Xiubo



Cheers,
--
Luís





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