Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753936AbbBZOJR (ORCPT ); Thu, 26 Feb 2015 09:09:17 -0500 Received: from mx1.redhat.com ([209.132.183.28]:59282 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753574AbbBZOJP (ORCPT ); Thu, 26 Feb 2015 09:09:15 -0500 From: Denys Vlasenko To: Andy Lutomirski Cc: Denys Vlasenko , Linus Torvalds , Steven Rostedt , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Oleg Nesterov , Frederic Weisbecker , Alexei Starovoitov , Will Drewry , Kees Cook , x86@kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] x86: fix a bug introduced by "allocate full pt_regs" commit Date: Thu, 26 Feb 2015 15:08:40 +0100 Message-Id: <1424959720-7628-1-git-send-email-dvlasenk@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1704 Lines: 48 If syscall_trace_enter_phase1 returns 0, code restores %rax from pt_regs->ax, but should restore it from pt_regs->orig_ax. The bug crept in because LOAD_ARGS macro was very sublty different from RESTORE_ARGS, it had only two callsites and only this one was using that difference. Signed-off-by: Denys Vlasenko CC: Linus Torvalds CC: Steven Rostedt CC: Ingo Molnar CC: Borislav Petkov CC: "H. Peter Anvin" CC: Andy Lutomirski CC: Oleg Nesterov CC: Frederic Weisbecker CC: Alexei Starovoitov CC: Will Drewry CC: Kees Cook CC: x86@kernel.org CC: linux-kernel@vger.kernel.org --- arch/x86/kernel/entry_64.S | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index da61974..519498d 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -316,7 +316,8 @@ tracesys: call syscall_trace_enter_phase1 test %rax, %rax jnz tracesys_phase2 /* if needed, run the slow path */ - RESTORE_C_REGS /* else restore clobbered regs */ + RESTORE_C_REGS_EXCEPT_RAX /* else restore clobbered regs */ + movq ORIG_RAX(%rsp), %rax jmp system_call_fastpath /* and return to the fast path */ tracesys_phase2: -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/