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 ENDBR to __vdso_sgx_enter_enclave() branch targets. Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: Jarkko Sakkinen <jarkko@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> --- arch/x86/entry/vdso/vsgx.S | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/entry/vdso/vsgx.S b/arch/x86/entry/vdso/vsgx.S index 86a0e94f68df..c63eafa54abd 100644 --- a/arch/x86/entry/vdso/vsgx.S +++ b/arch/x86/entry/vdso/vsgx.S @@ -4,6 +4,7 @@ #include <asm/export.h> #include <asm/errno.h> #include <asm/enclu.h> +#include <asm/vdso.h> #include "extable.h" @@ -27,6 +28,7 @@ SYM_FUNC_START(__vdso_sgx_enter_enclave) /* Prolog */ .cfi_startproc + ENDBR push %rbp .cfi_adjust_cfa_offset 8 .cfi_rel_offset %rbp, 0 @@ -62,6 +64,7 @@ SYM_FUNC_START(__vdso_sgx_enter_enclave) .Lasync_exit_pointer: .Lenclu_eenter_eresume: enclu + ENDBR /* EEXIT jumps here unless the enclave is doing something fancy. */ mov SGX_ENCLAVE_OFFSET_OF_RUN(%rbp), %rbx @@ -91,6 +94,7 @@ SYM_FUNC_START(__vdso_sgx_enter_enclave) jmp .Lout .Lhandle_exception: + ENDBR mov SGX_ENCLAVE_OFFSET_OF_RUN(%rbp), %rbx /* Set the exception info. */ -- 2.21.0
