Messages in this thread | | | Date | Fri, 16 Mar 2018 15:38:22 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH v2] rslib: Remove VLAs by setting upper bound on nroots |
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On Thu, 15 Mar 2018 15:59:19 -0700 Kees Cook <keescook@chromium.org> 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). > > [1] https://lkml.org/lkml/2018/3/7/621 > [2] https://lkml.org/lkml/2018/3/9/838
Yeah, email [2] is rather important. This patch is a bit of a pig to review!
The restriction to 24 roots might be a significant one, dunno. Perhaps we should just kmalloc these things?
Otherwise, RS_MAX_ROOTS becomes part of the rs interface and should be documented and published in rslib.h?
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