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

From: Kees Cook
Date: Wed Apr 28 2021 - 16:33:51 EST

On Tue, Apr 27, 2021 at 01:47:19PM -0700, Yu-cheng Yu wrote:
> From: "H.J. Lu" <>
> 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 <>

Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>

Kees Cook