From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932604AbcIMV3x (ORCPT ); Tue, 13 Sep 2016 17:29:53 -0400 Received: from mail.kernel.org ([198.145.29.136]:34408 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932548AbcIMV3u (ORCPT ); Tue, 13 Sep 2016 17:29:50 -0400 From: Andy Lutomirski To: x86@kernel.org Cc: Borislav Petkov , linux-kernel@vger.kernel.org, Brian Gerst , Jann Horn , Andy Lutomirski Subject: [PATCH 08/12] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Date: Tue, 13 Sep 2016 14:29:28 -0700 Message-Id: <7cd5e328dc75d8ccd912e5783665de34503f7c63.1473801993.git.luto@kernel.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This will prevent a crash if the target task dies before or while dumping its stack once we start freeing task stacks early. Signed-off-by: Andy Lutomirski --- arch/x86/kernel/stacktrace.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c index 4738f5e0f2ab..b3f32fbe3ba4 100644 --- a/arch/x86/kernel/stacktrace.c +++ b/arch/x86/kernel/stacktrace.c @@ -79,9 +79,14 @@ void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace) void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) { + if (!try_get_task_stack(tsk)) + return; + dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace); if (trace->nr_entries < trace->max_entries) trace->entries[trace->nr_entries++] = ULONG_MAX; + + put_task_stack(tsk); } EXPORT_SYMBOL_GPL(save_stack_trace_tsk); -- 2.7.4