Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx> writes: > On 02/20/2015 03:15 AM, Rusty Russell wrote: >> Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx> writes: >>> On 02/19/2015 02:10 AM, Rusty Russell wrote: >>>> This is not portable. Other archs don't use vmalloc, or don't use >>>> (or define) MODULES_VADDR. If you really want to hook here, you'd >>>> need a new flag (or maybe use PAGE_KERNEL_EXEC after an audit). >>>> >>> >>> Well, instead of explicit (addr >= MODULES_VADDR && addr < MODULES_END) >>> I could hide this into arch-specific function: 'kasan_need_to_allocate_shadow(const void *addr)' >>> or make make all those functions weak and allow arch code to redefine them. >> >> That adds another layer of indirection. And how would the caller of >> plain vmalloc() even know what to return? >> > > I think I don't understand what do you mean here. vmalloc() callers shouldn't know > anything about kasan/shadow. How else would kasan_need_to_allocate_shadow(const void *addr) work for architectures which don't have a reserved vmalloc region for modules? >> Hmm, how about a hybrid: >> >> 1) Add kasan_module_alloc(p, size) after module alloc as your original. >> 2) Hook into vfree(), and ignore it if you can't find the map. >> > > That should work, but it looks messy IMO. > >> Or is the latter too expensive? >> > > Not sure whether this will be too expensive or not, > but definitely more expensive than simple (addr >= MODULES_VADDR && addr < MODULES_END) check. Sure, if that check were portable. If you ever wanted kasan on other vmalloc addresses it wouldn't work either. I actually think this pattern is the *simplest* solution for auxilliary data like kasan. Cheers, Rusty. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>