Re: [PATCH v3 0/3] Assorted improvements to usercopy

[William Kucharski <william.kucharski@oracle.com>]

I like these, but a quick question:

Since the usercopy_abort() calls are all because the offset exceeds the page
size, is there a reason why you don't specifically state that via the detail
parameter rather than just supply a NULL pointer?

Otherwise for the patch series:

Reviewed-by: William Kucharski <william.kucharski@oracle.com>

> On Dec 13, 2021, at 7:27 AM, Matthew Wilcox (Oracle) <willy@infradead.org> wrote:
> 
> We must prohibit page boundary crossing for kmap() addresses.
> vmap() addresses are limited by the length of the mapping, and
> compound pages are limited by the size of the page.
> 
> These should probably all have test cases?
> 
> v3:
> - Remove a now-unused variable
> v2:
> - Prevent a NULL pointer dereference when a vmalloc-range pointer
>   doesn't have an associated allocation (me)
> - Report better offsets than "0" (Kees)
> 
> 
> Matthew Wilcox (Oracle) (3):
>  mm/usercopy: Check kmap addresses properly
>  mm/usercopy: Detect vmalloc overruns
>  mm/usercopy: Detect compound page overruns
> 
> arch/x86/include/asm/highmem.h   |  1 +
> include/linux/highmem-internal.h | 10 ++++++++
> mm/usercopy.c                    | 43 +++++++++++++++++++++++---------
> 3 files changed, 42 insertions(+), 12 deletions(-)
> 
> -- 
> 2.33.0