Re: [PATCH v2] rslib: Remove VLAs by setting upper bound on nroots

[Andrew Morton]

On Thu, 15 Mar 2018 15:59:19 -0700 Kees Cook <keescook@xxxxxxxxxxxx> wrote:

> Avoid stack VLAs[1] by always allocating the upper bound of stack space
> needed. The existing users of rslib appear to max out at 24 roots[2],
> so use that as the upper bound until we have a reason to change it.
> 
> Alternative considered: make init_rs() a true caller-instance and
> pre-allocate the workspaces. This would possibly need locking and
> a refactoring of the returned structure.
> 
> Using kmalloc in this path doesn't look great, especially since at
> least one caller (pstore) is sensitive to allocations during rslib
> usage (it expects to run it during an Oops, for example).

Oh.

Could we allocate the storage during init_rs(), attach it to `struct
rs_control'?