Re: [PATCH v26 8/9] x86/vdso/32: Add ENDBR to __kernel_vsyscall entry point

Kees Cook
2021-04-28T20:39:46Z

On Tue, Apr 27, 2021 at 01:47:19PM -0700, Yu-cheng Yu wrote:
> From: "H.J. Lu" <hjl.tools@gmail.com>
>
> ENDBR is a special new instruction for the Indirect Branch Tracking (IBT)
> component of CET. IBT prevents attacks by ensuring that (most) indirect
> branches and function calls may only land at ENDBR instructions. Branches
> that don't follow the rules will result in control flow (#CF) exceptions.
>
> ENDBR is a noop when IBT is unsupported or disabled. Most ENDBR
> instructions are inserted automatically by the compiler, but branch
> targets written in assembly must have ENDBR added manually.
>
> Add that to __kernel_vsyscall entry point.
>
> Signed-off-by: H.J. Lu <hjl.tools@gmail.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

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Kees Cook