linux-ext4 - Re: [PATCH 11/13] fuse: fix UAF in rcu pathwalks

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Date: Mon, 5 Feb 2024 13:31:47 +0100
From: Christian Brauner <brauner@...nel.org>
To: Al Viro <viro@...iv.linux.org.uk>
Cc: linux-fsdevel@...r.kernel.org, 
	Linus Torvalds <torvalds@...ux-foundation.org>, linux-ext4@...r.kernel.org, linux-nfs@...r.kernel.org, 
	Miklos Szeredi <miklos@...redi.hu>, linux-cifs@...r.kernel.org
Subject: Re: [PATCH 11/13] fuse: fix UAF in rcu pathwalks

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@...iv.linux.org.uk>
> ---

Reviewed-by: Christian Brauner <brauner@...nel.org>