On Wed, Oct 23, 2024 at 08:57:02AM +0200, Marco Elver wrote: > On Wed, 23 Oct 2024 at 08:53, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: > > > > On Fri, Oct 18, 2024 at 03:11:09PM +0000, Arnd Bergmann wrote: > > > From: Arnd Bergmann <arnd@xxxxxxxx> > > > > > > This symbol is now used on the kasan test module, so it needs to be > > > exported. > > > > > > ERROR: modpost: "copy_to_kernel_nofault" [mm/kasan/kasan_test.ko] undefined! > > > > Meh, it would be great not to export internal helpers just because > > someone wants to test them. Please just mark that test built-in only > > instead. > > We have EXPORT_SYMBOL_IF_KUNIT. See include/kunit/visibility.h - > that's more appropriate, and also adjust kasan_test.c to do > MODULE_IMPORT_NS(EXPORTED_FOR_KUNIT_TESTING). Thats a little better, but at least in this case I still think it is a very bad idea. copy_to_kernel_nofault is a perfect vector for exploit code to probe writing to kernel address without causing faults so it really should never ever be exported.
