Messages in this thread | ![/](/images/icornerl.gif) | | Date | Tue, 3 Oct 2023 13:46:20 -0700 | Subject | Re: [PATCH] x86_64: test that userspace stack is in fact NX | From | Dave Hansen <> |
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On 10/3/23 12:30, Ingo Molnar wrote: > * Ingo Molnar <mingo@kernel.org> wrote: >> Because not having NX in 2023 on any system that is threatened is a >> big security vulnerability in itself, and whether the vendor or owner >> intentionally did that or not doesn't really matter, and a failing >> kernel testcase will be the least of their problems. > BTW., it's also questionable whether the owner is *aware* of the fact that > NX is not available: what if some kernel debug option cleared the NX flag, > unintended, or there's some serious firmware bug? > > However unlikely those situations might be, I think unconditionally warning > about NX not available is a very 2023 thing to do.
100% agree for x86_64. Any sane x86_64 system has NX and the rest are noise that can live with the error message, unless someone shows up with a compelling reason why not.
For 32-bit, the situation is reversed. The majority of 32-bit-only CPUs never had NX. The only reason to even *do* this check on 32-bit is that we think folks are running i386 kernels on x86_64 hardware _or_ we just don't care about 32-bit in the first place.
In the end, I think if we're going to do this test on i386, we should _also_ do the 5-lines-of-code CPUID check. But I honestly don't care that much. I wouldn't NAK (or not merge) this patch over it.
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