On Tue, Jan 9, 2018 at 6:37 PM, Andrey Ryabinin <aryabi...@virtuozzo.com> wrote: > strscpy() performs the word-at-a-time optimistic reads. So it may > may access the memory past the end of the object, which is perfectly fine > since strscpy() doesn't use that (past-the-end) data and makes sure the > optimistic read won't cross a page boundary. > > But KASAN doesn't know anything about that so it will complain. > There are several possible ways to address this issue, but none > are perfect. See > https://lkml.kernel.org/r/9f0a9cf6-51f7-cd1f-5dc6-6d510a7b8...@virtuozzo.com > > It seems the best solution is to simply disable word-at-a-time > optimization. My trivial testing shows that byte-at-a-time > could be up to x4.3 times slower than word-at-a-time. > It may seems like a lot, but it's actually ~1.2e-10 sec per symbol vs > ~4.8e-10 sec per symbol on modern hardware. And we don't use strscpy() > in a performance critical paths to copy large amounts of data, > so it shouldn't matter anyway.
What prevents you to revert the patch? After this one the all advantages of the function becomes useless AFAIU. -- With Best Regards, Andy Shevchenko
