[kernel-hardening] Re: [PATCH 13/38] ext4: Define usercopy region in ext4_inode_cache slab cache

Theodore Ts'o
2018-01-11T17:01:19Z

On Wed, Jan 10, 2018 at 06:02:45PM -0800, Kees Cook wrote:
> The ext4 symlink pathnames, stored in struct ext4_inode_info.i_data
> and therefore contained in the ext4_inode_cache slab cache, need
> to be copied to/from userspace.

Symlink operations to/from userspace aren't common or in the hot path,
and when they are in i_data, limited to at most 60 bytes. Is it worth
it to copy through a bounce buffer so as to disallow any usercopies
into struct ext4_inode_info?

- Ted