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From: Amir Goldstein <amir73il@gmail.com>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: Christian Brauner <brauner@kernel.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	 linux-fsdevel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	 linux-ext4@vger.kernel.org, linux-nfs@vger.kernel.org,
	 linux-cifs@vger.kernel.org
Subject: Re: [PATCH 11/13] fuse: fix UAF in rcu pathwalks
Date: Mon, 4 Mar 2024 16:36:46 +0200	[thread overview]
Message-ID: <CAOQ4uxhBwmZ1LDcWD6jdaheUkDQAQUTeSNNMygRAg3v_0H5sDQ@mail.gmail.com> (raw)
In-Reply-To: <CAJfpegtJtrCTeRCT3w3qCLWsoDopePwUXmL5O9JtJfSJg17LNg@mail.gmail.com>

On Mon, Feb 5, 2024 at 3:52 PM Miklos Szeredi <miklos@szeredi.hu> wrote:
>
> On Mon, 5 Feb 2024 at 13:31, Christian Brauner <brauner@kernel.org> wrote:
> >
> > On Sun, Feb 04, 2024 at 02:17:37AM +0000, Al Viro wrote:
> > > ->permission(), ->get_link() and ->inode_get_acl() might dereference
> > > ->s_fs_info (and, in case of ->permission(), ->s_fs_info->fc->user_ns
> > > as well) when called from rcu pathwalk.
> > >
> > > Freeing ->s_fs_info->fc is rcu-delayed; we need to make freeing ->s_fs_info
> > > and dropping ->user_ns rcu-delayed too.
> > >
> > > Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
> > > ---
> >
> > Reviewed-by: Christian Brauner <brauner@kernel.org>
>
> Acked-by: Miklos Szeredi <mszeredi@redhat.com>
>

Miklos,

FYI, this is now merged and conflicts with:

dc076c73b9f9 ("fuse: implement ioctls to manage backing files")

from fuse/for-next:

--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@@ -1373,7 -1398,9 +1405,13 @@@ EXPORT_SYMBOL_GPL(fuse_send_init)
  void fuse_free_conn(struct fuse_conn *fc)
  {
        WARN_ON(!list_empty(&fc->devices));
++<<<<<<< HEAD
 +      kfree(fc);
++=======
+       if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
+               fuse_backing_files_free(fc);
+       kfree_rcu(fc, rcu);
++>>>>>>> fuse/for-next
  }
  EXPORT_SYMBOL_GPL(fuse_free_conn);

Note that fuse_backing_files_free() calls
fuse_backing_id_free() => fuse_backing_free() => kfree_rcu()

Should we move fuse_backing_files_free() into
fuse_conn_put() above fuse_dax_conn_free()?

That will avoid the merge conflict and still be correct. no?

Thanks,
Amir.

  reply	other threads:[~2024-03-04 14:36 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-04  2:14 [PATCHES] RCU pathwalk race fixes Al Viro
2024-02-04  2:17 ` [PATCH 01/13] fs/super.c: don't drop ->s_user_ns until we free struct super_block itself Al Viro
2024-02-04  2:17   ` [PATCH 02/13] rcu pathwalk: prevent bogus hard errors from may_lookup() Al Viro
2024-02-05 12:26     ` Christian Brauner
2024-02-04  2:17   ` [PATCH 03/13] affs: free affs_sb_info with kfree_rcu() Al Viro
2024-02-05 12:26     ` Christian Brauner
2024-02-04  2:17   ` [PATCH 04/13] exfat: move freeing sbi, upcase table and dropping nls into rcu-delayed helper Al Viro
2024-02-05 12:27     ` Christian Brauner
2024-02-04  2:17   ` [PATCH 05/13] hfsplus: switch to rcu-delayed unloading of nls and freeing ->s_fs_info Al Viro
2024-02-05 12:27     ` Christian Brauner
2024-02-04  2:17   ` [PATCH 06/13] afs: fix __afs_break_callback() / afs_drop_open_mmap() race Al Viro
2024-02-05 12:28     ` Christian Brauner
2024-02-04  2:17   ` [PATCH 07/13] nfs: make nfs_set_verifier() safe for use in RCU pathwalk Al Viro
2024-02-05 12:29     ` Christian Brauner
2024-02-04  2:17   ` [PATCH 08/13] nfs: fix UAF on pathwalk running into umount Al Viro
2024-02-05 12:29     ` Christian Brauner
2024-02-04  2:17   ` [PATCH 09/13] procfs: move dropping pde and pid from ->evict_inode() to ->free_inode() Al Viro
2024-02-05 12:30     ` Christian Brauner
2024-02-04  2:17   ` [PATCH 10/13] procfs: make freeing proc_fs_info rcu-delayed Al Viro
2024-02-05 12:31     ` Christian Brauner
2024-02-04  2:17   ` [PATCH 11/13] fuse: fix UAF in rcu pathwalks Al Viro
2024-02-05 12:31     ` Christian Brauner
2024-02-05 13:51       ` Miklos Szeredi
2024-03-04 14:36         ` Amir Goldstein [this message]
2024-03-05 12:43           ` Miklos Szeredi
2024-03-06 10:18             ` Amir Goldstein
2024-03-06 10:21               ` Miklos Szeredi
2024-02-04  2:17   ` [PATCH 12/13] cifs_get_link(): bail out in unsafe case Al Viro
2024-02-04 15:45     ` Steve French
2024-02-04 16:25       ` Al Viro
2024-02-04 16:41         ` Al Viro
2024-02-04  2:17   ` [PATCH 13/13] ext4_get_link(): fix breakage in RCU mode Al Viro
2024-02-05 12:24   ` [PATCH 01/13] fs/super.c: don't drop ->s_user_ns until we free struct super_block itself Christian Brauner
2024-02-05 12:36   ` Jeff Layton
2024-02-04  2:27 ` RCU pathwalk audit notes Al Viro
2024-02-05 12:48 ` [PATCHES] RCU pathwalk race fixes Jeff Layton

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