From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761385Ab2KBAQR (ORCPT ); Thu, 1 Nov 2012 20:16:17 -0400 Received: from smtp.outflux.net ([198.145.64.163]:48954 "EHLO smtp.outflux.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758642Ab2KBAQN (ORCPT ); Thu, 1 Nov 2012 20:16:13 -0400 From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Russell King , Will Deacon , Will Drewry , Geremy Condra , Al Viro , Catalin Marinas , Kees Cook Subject: [PATCH 3/4] arch/arm: allow a scno of -1 to not cause a SIGILL Date: Thu, 1 Nov 2012 17:14:59 -0700 Message-Id: <1351815300-28627-4-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1351815300-28627-1-git-send-email-keescook@chromium.org> References: <1351815300-28627-1-git-send-email-keescook@chromium.org> X-HELO: www.outflux.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On tracehook-friendly platforms, a system call number of -1 falls through without running much code or taking much action. ARM is different. This adds a short-circuit check in the trace path to avoid any additional work, as suggested by Russell King, to make sure that ARM behaves the same way as other platforms. Signed-off-by: Kees Cook --- arch/arm/kernel/entry-common.S | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index 8355d4b..0bef977 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -448,7 +448,10 @@ __sys_trace: ldmccia r1, {r0 - r6} @ have to reload r0 - r6 stmccia sp, {r4, r5} @ and update the stack args ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine - b 2b + cmp scno, #-1 @ skip the syscall? + bne 2b + add sp, sp, #S_OFF @ restore stack + b ret_slow_syscall __sys_trace_return: str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 -- 1.7.9.5