Re: [PATCH v2] fs: fix UAF/GPF bug in nilfs_mdt_destroy

[Christian Brauner]

On Tue, Aug 16, 2022 at 12:08:58PM +0800, Dongliang Mu wrote:
> From: Dongliang Mu <mudongliangabcd@xxxxxxxxx>
> 
> In alloc_inode, inode_init_always() could return -ENOMEM if
> security_inode_alloc() fails, which causes inode->i_private
> uninitialized. Then nilfs_is_metadata_file_inode() returns
> true and nilfs_free_inode() wrongly calls nilfs_mdt_destroy(),
> which frees the uninitialized inode->i_private
> and leads to crashes(e.g., UAF/GPF).
> 
> Fix this by moving security_inode_alloc just prior to
> this_cpu_inc(nr_inodes)
> 
> Link: https://lkml.kernel.org/r/CAFcO6XOcf1Jj2SeGt=jJV59wmhESeSKpfR0omdFRq+J9nD1vfQ@xxxxxxxxxxxxxx
> Reported-by: butt3rflyh4ck <butterflyhuangxx@xxxxxxxxx>
> Reported-by: Hao Sun <sunhao.th@xxxxxxxxx>
> Reported-by: Jiacheng Xu <stitch@xxxxxxxxxx>
> Signed-off-by: Dongliang Mu <mudongliangabcd@xxxxxxxxx>
> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---

Looks good to me,
Reviewed-by: Christian Brauner (Microsoft) <brauner@xxxxxxxxxx>