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> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> 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 99dafac992e2..c7cb85d57b3f 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 + ENDBR64 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 + ENDBR64 /* 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: + ENDBR64 mov SGX_ENCLAVE_OFFSET_OF_RUN(%rbp), %rbx /* Set the exception info. */ -- 2.21.0
