lkdtm: Do not use flush_icache_range() on user addresses
The flush_icache_range() API is meant to be used on kernel addresses only as it may not have the infrastructure (exception entries) to handle user memory faults. The lkdtm execute_user_location() function tests the kernel execution of user space addresses by mmap'ing an anonymous page, copying some code together with cache maintenance and attempting to run it. However, the cache maintenance step may fail because of the incorrect API usage described above. The patch changes lkdtm to use access_process_vm() for copying the code into user space which would take care of the necessary cache maintenance. Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com> [kees: export access_process_vm() for module use] Signed-off-by: NKees Cook <keescook@chromium.org> Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
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