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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id ECCEBC54EB4 for ; Sun, 22 Jan 2023 15:18:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231171AbjAVPSR (ORCPT ); Sun, 22 Jan 2023 10:18:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45272 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231162AbjAVPSN (ORCPT ); Sun, 22 Jan 2023 10:18:13 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF6123AB5 for ; Sun, 22 Jan 2023 07:18:12 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 7B98B60C48 for ; Sun, 22 Jan 2023 15:18:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8E1C5C433D2; Sun, 22 Jan 2023 15:18:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1674400691; bh=qVWf0RJkRGfrQTd+FUM4b4Swu6f7nlndQ+Oa8K42xCw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sH/L936GIU73lefpfCebgzKRePcR83JrDStC4DusRY1+NLV1NFsfIf65vHt7Mz7LQ UcRMCzzl1FDqtTFyJaq+ndjuOCnLsweYk6dm7L+gv0tZG6yoMf09fi5YEP932s6374 UkV5GXFH11Rba+Lub53llBu/v6y8Rn+adfHQqnFQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Gaosheng Cui , Samuel Thibault Subject: [PATCH 5.15 073/117] tty: fix possible null-ptr-defer in spk_ttyio_release Date: Sun, 22 Jan 2023 16:04:23 +0100 Message-Id: <20230122150235.832235416@linuxfoundation.org> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230122150232.736358800@linuxfoundation.org> References: <20230122150232.736358800@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Gaosheng Cui commit 5abbeebd8296c2301023b8dc4b5a6c0d5229b4f5 upstream. Run the following tests on the qemu platform: syzkaller:~# modprobe speakup_audptr input: Speakup as /devices/virtual/input/input4 initialized device: /dev/synth, node (MAJOR 10, MINOR 125) speakup 3.1.6: initialized synth name on entry is: (null) synth probe spk_ttyio_initialise_ldisc failed because tty_kopen_exclusive returned failed (errno -16), then remove the module, we will get a null-ptr-defer problem, as follow: syzkaller:~# modprobe -r speakup_audptr releasing synth audptr BUG: kernel NULL pointer dereference, address: 0000000000000080 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] PREEMPT SMP PTI CPU: 2 PID: 204 Comm: modprobe Not tainted 6.1.0-rc6-dirty #1 RIP: 0010:mutex_lock+0x14/0x30 Call Trace: spk_ttyio_release+0x19/0x70 [speakup] synth_release.part.6+0xac/0xc0 [speakup] synth_remove+0x56/0x60 [speakup] __x64_sys_delete_module+0x156/0x250 ? fpregs_assert_state_consistent+0x1d/0x50 do_syscall_64+0x37/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd Modules linked in: speakup_audptr(-) speakup Dumping ftrace buffer: in_synth->dev was not initialized during modprobe, so we add check for in_synth->dev to fix this bug. Fixes: 4f2a81f3a882 ("speakup: Reference synth from tty and tty from synth") Cc: stable Signed-off-by: Gaosheng Cui Link: https://lore.kernel.org/r/20221202060633.217364-1-cuigaosheng1@huawei.com Reviewed-by: Samuel Thibault Signed-off-by: Greg Kroah-Hartman --- drivers/accessibility/speakup/spk_ttyio.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/accessibility/speakup/spk_ttyio.c +++ b/drivers/accessibility/speakup/spk_ttyio.c @@ -354,6 +354,9 @@ void spk_ttyio_release(struct spk_synth { struct tty_struct *tty = in_synth->dev; + if (tty == NULL) + return; + tty_lock(tty); if (tty->ops->close)