From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932700AbcGKU43 (ORCPT ); Mon, 11 Jul 2016 16:56:29 -0400 Received: from mail.kernel.org ([198.145.29.136]:35350 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932562AbcGKUyz (ORCPT ); Mon, 11 Jul 2016 16:54:55 -0400 From: Andy Lutomirski To: x86@kernel.org, linux-kernel@vger.kernel.org Cc: linux-arch@vger.kernel.org, Borislav Petkov , Nadav Amit , Kees Cook , Brian Gerst , "kernel-hardening@lists.openwall.com" , Linus Torvalds , Josh Poimboeuf , Jann Horn , Heiko Carstens , Andy Lutomirski Subject: [PATCH v5 30/32] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Date: Mon, 11 Jul 2016 13:54:03 -0700 Message-Id: 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 9ee98eefc44d..cc0826409a21 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