From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BB2C1C2D0CE for ; Fri, 3 Jan 2020 03:46:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7AC0D206DA for ; Fri, 3 Jan 2020 03:46:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="SyToewWL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727133AbgACDqB (ORCPT ); Thu, 2 Jan 2020 22:46:01 -0500 Received: from mail-pg1-f193.google.com ([209.85.215.193]:45664 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726112AbgACDqB (ORCPT ); Thu, 2 Jan 2020 22:46:01 -0500 Received: by mail-pg1-f193.google.com with SMTP id b9so22824508pgk.12 for ; Thu, 02 Jan 2020 19:46:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=XGzDwEKryl/njIEsg+eGczbmkTamUbnwIpvGpsNWo24=; b=SyToewWLwMb/Q8NsXcEypx9gH0lNVlm+4vKTWg9+WdHhDut2aZCy+rBvmk1/+7Emtl 42SUQsmu3vIPZpeMpGSpwo/u/h8fEmG/CzX75+HKjbJ04gM7t+SKqbbOvosnIpPojyuL JKeETirGcMXcYlbPF+jcmTcjisIthyXBpwgUFHs2WZtk5wpalI5R6bzvi0OngEci64LQ lwqDFWpuT7P08dpUirumpmdegy13c/qwHQ9BOb3pBH42ZhDW/ffGmKVBMkfhT1W7qCyk 03RfJZiOzuWzDPhN76Jrrk2QrEth63NLic15qDXKCR32x83kqeidsXN6GNxYn5o9Mqgg iIqg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=XGzDwEKryl/njIEsg+eGczbmkTamUbnwIpvGpsNWo24=; b=OyECOrm3ZLai+h8GKs3ZXAmHKd7HA4cyadwYu8f4sLqt0Oxt47BUWPjFdPGBVuUTnX ZCD7CzPbOp18UAiQvKB1U7eDlG86Ci8VFXWcYwyYjR1ujcb2uqLQ9SghLMHiHcPhr2bS 36rbtdF+62ZehSMCx3X3EP6k/iMNspeZ7X6oC8IOZcXv3r2df5gW5Ice3dhlT/YIBBXF uQvFtLP66zCYLY2VyoYtHW9P7jmkmFnly3Jb5qQwqU90b9TY3baSEslfgJ7R/A3vwhXe LDl3/vM1s7GUPheIARAoyJnA6asG7+LTB/NluGg659caFbAsgK3bmIV4EkJgu3+oArcr /WQQ== X-Gm-Message-State: APjAAAUwqfuxLypykYcvAZ+9TnVgq7TUueB9UM1hyyJz+dU409mSw3tK 6ikpKCe0+WYnd3YKJAOPKy6+a6Cg/kR/hQ== X-Google-Smtp-Source: APXvYqwuzgCuL9MdQUcSAqoCuGCNWz7idXlWIdQauSLL3yrSUda3WTyXiy/9JPi3R6PKYu3yxE2Esg== X-Received: by 2002:a63:5243:: with SMTP id s3mr90794069pgl.449.1578023159961; Thu, 02 Jan 2020 19:45:59 -0800 (PST) Received: from ZB-PF114XEA.360buyad.local ([103.90.76.242]) by smtp.gmail.com with ESMTPSA id z4sm12561907pjn.29.2020.01.02.19.45.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 02 Jan 2020 19:45:59 -0800 (PST) From: Zhenzhong Duan To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, Zhenzhong Duan , Arnd Bergmann , Greg Kroah-Hartman Subject: [PATCH RESEND] ttyprintk: fix a potential sleeping in interrupt context issue Date: Fri, 3 Jan 2020 11:45:41 +0800 Message-Id: <20200103034541.5302-1-zhenzhong.duan@gmail.com> X-Mailer: git-send-email 2.17.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Google syzbot reports: BUG: sleeping function called from invalid context at kernel/locking/mutex.c:938 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 0, name: swapper/1 1 lock held by swapper/1/0: ... Call Trace: dump_stack+0x197/0x210 ___might_sleep.cold+0x1fb/0x23e __might_sleep+0x95/0x190 __mutex_lock+0xc5/0x13c0 mutex_lock_nested+0x16/0x20 tpk_write+0x5d/0x340 resync_tnc+0x1b6/0x320 call_timer_fn+0x1ac/0x780 run_timer_softirq+0x6c3/0x1790 __do_softirq+0x262/0x98c irq_exit+0x19b/0x1e0 smp_apic_timer_interrupt+0x1a3/0x610 apic_timer_interrupt+0xf/0x20 Fix it by using spinlock in process context instead of mutex and having interrupt disabled in critical section. Signed-off-by: Zhenzhong Duan Cc: Arnd Bergmann Cc: Greg Kroah-Hartman --- drivers/char/ttyprintk.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/drivers/char/ttyprintk.c b/drivers/char/ttyprintk.c index 4f24e46ebe7c..56db949a7b70 100644 --- a/drivers/char/ttyprintk.c +++ b/drivers/char/ttyprintk.c @@ -15,10 +15,11 @@ #include #include #include +#include struct ttyprintk_port { struct tty_port port; - struct mutex port_write_mutex; + spinlock_t spinlock; }; static struct ttyprintk_port tpk_port; @@ -99,11 +100,12 @@ static int tpk_open(struct tty_struct *tty, struct file *filp) static void tpk_close(struct tty_struct *tty, struct file *filp) { struct ttyprintk_port *tpkp = tty->driver_data; + unsigned long flags; - mutex_lock(&tpkp->port_write_mutex); + spin_lock_irqsave(&tpkp->spinlock, flags); /* flush tpk_printk buffer */ tpk_printk(NULL, 0); - mutex_unlock(&tpkp->port_write_mutex); + spin_unlock_irqrestore(&tpkp->spinlock, flags); tty_port_close(&tpkp->port, tty, filp); } @@ -115,13 +117,14 @@ static int tpk_write(struct tty_struct *tty, const unsigned char *buf, int count) { struct ttyprintk_port *tpkp = tty->driver_data; + unsigned long flags; int ret; /* exclusive use of tpk_printk within this tty */ - mutex_lock(&tpkp->port_write_mutex); + spin_lock_irqsave(&tpkp->spinlock, flags); ret = tpk_printk(buf, count); - mutex_unlock(&tpkp->port_write_mutex); + spin_unlock_irqrestore(&tpkp->spinlock, flags); return ret; } @@ -171,7 +174,7 @@ static int __init ttyprintk_init(void) { int ret = -ENOMEM; - mutex_init(&tpk_port.port_write_mutex); + spin_lock_init(&tpk_port.spinlock); ttyprintk_driver = tty_alloc_driver(1, TTY_DRIVER_RESET_TERMIOS | -- 2.17.1