Messages in this thread | | | From | Jann Horn <> | Date | Thu, 4 Jun 2020 16:01:30 +0200 | Subject | Re: [PATCH 1/5] gcc-plugins/stackleak: Exclude alloca() from the instrumentation logic |
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On Thu, Jun 4, 2020 at 3:51 PM Alexander Popov <alex.popov@linux.com> wrote: > Some time ago Variable Length Arrays (VLA) were removed from the kernel. > The kernel is built with '-Wvla'. Let's exclude alloca() from the > instrumentation logic and make it simpler. The build-time assertion > against alloca() is added instead. [...] > + /* Variable Length Arrays are forbidden in the kernel */ > + gcc_assert(!is_alloca(stmt));
There is a patch series from Elena and Kees on the kernel-hardening list that deliberately uses __builtin_alloca() in the syscall entry path to randomize the stack pointer per-syscall - see <https://lore.kernel.org/kernel-hardening/20200406231606.37619-4-keescook@chromium.org/>.
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