Re: [PATCH] files: rcu free files_struct

[Al Viro]

On Thu, Dec 10, 2020 at 11:30:24PM +0100, Christian Brauner wrote:
> (requiring btf), i.e. security_file_open, then follow
> file->f_inode->i_sb->s_type->s_magic. If we change the say struct
> super_block I'd expect these bpf programs to break.

To break they would need to have compiled in the first place;
->s_type is struct file_system_type and it contains no ->s_magic
(nor would it be possible, really - ->s_magic can vary between
filesystems that *do* share ->s_type).