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Lu" Cc: Florian Weimer , "Kirill A. Shutemov" , "Shanbhogue, Vedvyas" , "H.J. 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Lu wrote: > > We are working to enable LAM in glibc and GCC (HWASAN). > > 0. LAM is disabled when the process starts. > 1. Define GNU property markers for LAM compatibility. > 2. Update ld.so to support LAM. > 3. Make libc.so LAM compatible (memmove). if pointers to the same object always have the same tag, then memmove should work without changes i think. if such pointers can have different tags then all pointer comparisions are problematic, not just memmove. > 4. Provide an API to enable LAM. > > We noticed a few issues: > > 1. HWASAN should use the glibc API to enable tagged address > since glibc must track the tagged address mask. how does that mask work? is it possible to set it to different values or just on/off? > 2. set_tagged_address_mask shouldn't be allowed after > pthread_create is called. such api breaks software composability. i don't have a good solution (other than libc doing an early decision on its own). > 3. After set_tagged_address_mask is called, can it be called > again to change tagged address mask. after tagged pointers escape it is unlikely that changing settings works.