From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755651AbcAXW0R (ORCPT ); Sun, 24 Jan 2016 17:26:17 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:60779 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755412AbcAXWDo (ORCPT ); Sun, 24 Jan 2016 17:03:44 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Peter Hurley , Greg Kroah-Hartman , Luis Henriques Subject: [PATCH 3.16.y-ckt 063/128] tty: Fix GPF in flush_to_ldisc() Date: Sun, 24 Jan 2016 22:00:18 +0000 Message-Id: <1453672883-2708-64-git-send-email-luis.henriques@canonical.com> In-Reply-To: <1453672883-2708-1-git-send-email-luis.henriques@canonical.com> References: <1453672883-2708-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.7-ckt23 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Peter Hurley commit 9ce119f318ba1a07c29149301f1544b6c4bea52a upstream. A line discipline which does not define a receive_buf() method can can cause a GPF if data is ever received [1]. Oddly, this was known to the author of n_tracesink in 2011, but never fixed. [1] GPF report BUG: unable to handle kernel NULL pointer dereference at (null) IP: [< (null)>] (null) PGD 3752d067 PUD 37a7b067 PMD 0 Oops: 0010 [#1] SMP KASAN Modules linked in: CPU: 2 PID: 148 Comm: kworker/u10:2 Not tainted 4.4.0-rc2+ #51 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Workqueue: events_unbound flush_to_ldisc task: ffff88006da94440 ti: ffff88006db60000 task.ti: ffff88006db60000 RIP: 0010:[<0000000000000000>] [< (null)>] (null) RSP: 0018:ffff88006db67b50 EFLAGS: 00010246 RAX: 0000000000000102 RBX: ffff88003ab32f88 RCX: 0000000000000102 RDX: 0000000000000000 RSI: ffff88003ab330a6 RDI: ffff88003aabd388 RBP: ffff88006db67c48 R08: ffff88003ab32f9c R09: ffff88003ab31fb0 R10: ffff88003ab32fa8 R11: 0000000000000000 R12: dffffc0000000000 R13: ffff88006db67c20 R14: ffffffff863df820 R15: ffff88003ab31fb8 FS: 0000000000000000(0000) GS:ffff88006dc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000000 CR3: 0000000037938000 CR4: 00000000000006e0 Stack: ffffffff829f46f1 ffff88006da94bf8 ffff88006da94bf8 0000000000000000 ffff88003ab31fb0 ffff88003aabd438 ffff88003ab31ff8 ffff88006430fd90 ffff88003ab32f9c ffffed0007557a87 1ffff1000db6cf78 ffff88003ab32078 Call Trace: [] process_one_work+0x8f1/0x17a0 kernel/workqueue.c:2030 [] worker_thread+0xd4/0x1180 kernel/workqueue.c:2162 [] kthread+0x1cf/0x270 drivers/block/aoe/aoecmd.c:1302 [] ret_from_fork+0x3f/0x70 arch/x86/entry/entry_64.S:468 Code: Bad RIP value. RIP [< (null)>] (null) RSP CR2: 0000000000000000 ---[ end trace a587f8947e54d6ea ]--- Reported-by: Dmitry Vyukov Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman Signed-off-by: Luis Henriques --- drivers/tty/tty_buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c index 143deb62467d..12446e9a4435 100644 --- a/drivers/tty/tty_buffer.c +++ b/drivers/tty/tty_buffer.c @@ -411,7 +411,7 @@ receive_buf(struct tty_struct *tty, struct tty_buffer *head, int count) count = disc->ops->receive_buf2(tty, p, f, count); else { count = min_t(int, count, tty->receive_room); - if (count) + if (count && disc->ops->receive_buf) disc->ops->receive_buf(tty, p, f, count); } head->read += count;