From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759331AbcIPJS5 (ORCPT ); Fri, 16 Sep 2016 05:18:57 -0400 Received: from terminus.zytor.com ([198.137.202.10]:37140 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754490AbcIPJSt (ORCPT ); Fri, 16 Sep 2016 05:18:49 -0400 Date: Fri, 16 Sep 2016 02:17:46 -0700 From: tip-bot for Andy Lutomirski Message-ID: Cc: luto@kernel.org, hpa@zytor.com, jpoimboe@redhat.com, mingo@kernel.org, dvlasenk@redhat.com, linux-kernel@vger.kernel.org, jann@thejh.net, peterz@infradead.org, torvalds@linux-foundation.org, brgerst@gmail.com, tglx@linutronix.de, bp@alien8.de Reply-To: jann@thejh.net, torvalds@linux-foundation.org, peterz@infradead.org, tglx@linutronix.de, bp@alien8.de, brgerst@gmail.com, luto@kernel.org, hpa@zytor.com, jpoimboe@redhat.com, mingo@kernel.org, linux-kernel@vger.kernel.org, dvlasenk@redhat.com In-Reply-To: References: To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/asm] x86/dumpstack: Pin the target stack when dumping it Git-Commit-ID: 1959a60182f48879635812a03a99c02231ea8677 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 1959a60182f48879635812a03a99c02231ea8677 Gitweb: http://git.kernel.org/tip/1959a60182f48879635812a03a99c02231ea8677 Author: Andy Lutomirski AuthorDate: Thu, 15 Sep 2016 22:45:45 -0700 Committer: Ingo Molnar CommitDate: Fri, 16 Sep 2016 09:18:53 +0200 x86/dumpstack: Pin the target stack when dumping it Specifically, pin the stack in save_stack_trace_tsk() and show_trace_log_lvl(). 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 Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jann Horn Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/cf0082cde65d1941a996d026f2b2cdbfaca17bfa.1474003868.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/kernel/dumpstack_32.c | 5 +++++ arch/x86/kernel/dumpstack_64.c | 5 +++++ arch/x86/kernel/stacktrace.c | 5 +++++ 3 files changed, 15 insertions(+) diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c index 2d65cfa..122f37d7 100644 --- a/arch/x86/kernel/dumpstack_32.c +++ b/arch/x86/kernel/dumpstack_32.c @@ -163,6 +163,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, unsigned long *stack; int i; + if (!try_get_task_stack(task)) + return; + sp = sp ? : get_stack_pointer(task, regs); stack = sp; @@ -179,6 +182,8 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, } pr_cont("\n"); show_trace_log_lvl(task, regs, sp, bp, log_lvl); + + put_task_stack(task); } diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c index 8cb6004..16c0d5f 100644 --- a/arch/x86/kernel/dumpstack_64.c +++ b/arch/x86/kernel/dumpstack_64.c @@ -218,6 +218,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, unsigned long *stack; int i; + if (!try_get_task_stack(task)) + return; + irq_stack_end = (unsigned long *)this_cpu_read(irq_stack_ptr); irq_stack = irq_stack_end - (IRQ_STACK_SIZE / sizeof(long)); @@ -253,6 +256,8 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, pr_cont("\n"); show_trace_log_lvl(task, regs, sp, bp, log_lvl); + + put_task_stack(task); } void show_regs(struct pt_regs *regs) diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c index 785aef1..23fa81e 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);