* Andy Lutomirski: > On Mon, Aug 24, 2020 at 5:30 PM Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx> wrote: >> >> From: "H.J. Lu" <hjl.tools@xxxxxxxxx> >> >> Emulation of the legacy vsyscall page is required by some programs built >> before 2013. Newer programs after 2013 don't use it. Disallow vsyscall >> emulation when Control-flow Enforcement (CET) is enabled to enhance >> security. > > NAK. > > By all means disable execute emulation if CET-IBT is enabled at the > time emulation is attempted, and maybe even disable the vsyscall page > entirely if you can magically tell that CET-IBT will be enabled when a > process starts, but you don't get to just disable it outright on a > CET-enabled kernel. Yeah, we definitely would have to revert/avoid this downstream. People definitely want to run glibc-2.12-era workloads on current kernels. Thanks for catching it. Florian
