Re: [PATCH 4/6] powerpc/spufs: check permissions in spufs_setattr()

[Arnd Bergmann]

On Sun, Aug 2, 2026, at 17:51, Junrui Luo via B4 Relay wrote:
> From: Junrui Luo <moonafterrain@xxxxxxxxxxx>
>
> spufs_setattr() applies the caller's attributes with setattr_copy() but
> never calls setattr_prepare(). notify_change() leaves that to the
> filesystem: it runs only may_setattr(), while inode_owner_or_capable()
> and the CAP_CHOWN test live inside setattr_prepare(). setattr_copy()
> performs no checking of its own.
>
> The handler is installed for every regular spufs file, so mode and
> ownership of another user's context files can be changed without the
> usual authorization.
>
> Call setattr_prepare() before setattr_copy(). The existing ATTR_SIZE
> test stays ahead of it so that resizing a spufs file keeps returning
> -EINVAL. &nop_mnt_idmap matches the adjacent setattr_copy() call.
>
> Fixes: 67207b9664a8 ("[PATCH] spufs: The SPU file system, base")
> Reported-by: Yuhao Jiang <danisjiang@xxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Junrui Luo <moonafterrain@xxxxxxxxxxx>

Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>