On Wed, Aug 17, 2016 at 2:45 PM, Linus Torvalds <[email protected]> wrote: > On Wed, Aug 17, 2016 at 2:37 PM, Rik van Riel <[email protected]> wrote: >> >> This particular allocation is through kmalloc, but the >> kernel in question has CONFIG_SLOB=y, and usercopy has >> no code in mm/slob.c > > Oh, I didn't notice that. > > Maybe we can just say that HARDENING depends on !SLOB for now, and see > if anything else shows up.
This logic (for avoiding uninstrumented allocators, which is only SLOB) already exists (via CONFIG_HAVE_HARDENED_USERCOPY_ALLOCATOR). And PageSlab(page) should be catching this, so that the logic of "this is from the allocator, so we must use its checker" is supposed to get invoked. > Maybe we don't have any code that copies data from (non-kmalloc) > multi-order allocations to user space. > > Networking does, but seems to use __GFP_COMP, at least in the one case > I checked (skbuff). Was this allocation really through kmalloc? -Kees -- Kees Cook Nexus Security
