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 F0712C25B08 for ; Mon, 15 Aug 2022 18:28:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242477AbiHOS2s (ORCPT ); Mon, 15 Aug 2022 14:28:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54586 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242801AbiHOS02 (ORCPT ); Mon, 15 Aug 2022 14:26:28 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 841DE2AE14; Mon, 15 Aug 2022 11:19:28 -0700 (PDT) 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 A970F6069E; Mon, 15 Aug 2022 18:18:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB1B4C433D6; Mon, 15 Aug 2022 18:18:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660587534; bh=UsJ1W9RjJSWVKtc1ccZK/Q+wChESlZoqtnuUpz+5rhc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NSLPKZzdxW+FAWW2j7+XQoRcikG5D9mdzgfXYqvi2pY9gSftXrheJszgKWv6YUplh mQSn3x5zk59ugIhV56nMauxG9fFg6nx/STvkrPV/91/xD740jbsTN9qtXTtu8Qmpx1 XWvet6jJvi2INBX8eB7V+1R8Mut3pdQSorNyLtLs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, hewenliang , Haibin Zhang , Catalin Marinas , Will Deacon , Sasha Levin Subject: [PATCH 5.15 114/779] arm64: fix oops in concurrently setting insn_emulation sysctls Date: Mon, 15 Aug 2022 19:55:58 +0200 Message-Id: <20220815180342.196857372@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815180337.130757997@linuxfoundation.org> References: <20220815180337.130757997@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: linux-kernel@vger.kernel.org From: haibinzhang (张海斌) [ Upstream commit af483947d472eccb79e42059276c4deed76f99a6 ] emulation_proc_handler() changes table->data for proc_dointvec_minmax and can generate the following Oops if called concurrently with itself: | Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 | Internal error: Oops: 96000006 [#1] SMP | Call trace: | update_insn_emulation_mode+0xc0/0x148 | emulation_proc_handler+0x64/0xb8 | proc_sys_call_handler+0x9c/0xf8 | proc_sys_write+0x18/0x20 | __vfs_write+0x20/0x48 | vfs_write+0xe4/0x1d0 | ksys_write+0x70/0xf8 | __arm64_sys_write+0x20/0x28 | el0_svc_common.constprop.0+0x7c/0x1c0 | el0_svc_handler+0x2c/0xa0 | el0_svc+0x8/0x200 To fix this issue, keep the table->data as &insn->current_mode and use container_of() to retrieve the insn pointer. Another mutex is used to protect against the current_mode update but not for retrieving insn_emulation as table->data is no longer changing. Co-developed-by: hewenliang Signed-off-by: hewenliang Signed-off-by: Haibin Zhang Reviewed-by: Catalin Marinas Link: https://lore.kernel.org/r/20220128090324.2727688-1-hewenliang4@huawei.com Link: https://lore.kernel.org/r/9A004C03-250B-46C5-BF39-782D7551B00E@tencent.com Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- arch/arm64/kernel/armv8_deprecated.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c index 0e86e8b9cedd..c5da9d1e954a 100644 --- a/arch/arm64/kernel/armv8_deprecated.c +++ b/arch/arm64/kernel/armv8_deprecated.c @@ -59,6 +59,7 @@ struct insn_emulation { static LIST_HEAD(insn_emulation); static int nr_insn_emulated __initdata; static DEFINE_RAW_SPINLOCK(insn_emulation_lock); +static DEFINE_MUTEX(insn_emulation_mutex); static void register_emulation_hooks(struct insn_emulation_ops *ops) { @@ -207,10 +208,10 @@ static int emulation_proc_handler(struct ctl_table *table, int write, loff_t *ppos) { int ret = 0; - struct insn_emulation *insn = (struct insn_emulation *) table->data; + struct insn_emulation *insn = container_of(table->data, struct insn_emulation, current_mode); enum insn_emulation_mode prev_mode = insn->current_mode; - table->data = &insn->current_mode; + mutex_lock(&insn_emulation_mutex); ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); if (ret || !write || prev_mode == insn->current_mode) @@ -223,7 +224,7 @@ static int emulation_proc_handler(struct ctl_table *table, int write, update_insn_emulation_mode(insn, INSN_UNDEF); } ret: - table->data = insn; + mutex_unlock(&insn_emulation_mutex); return ret; } @@ -247,7 +248,7 @@ static void __init register_insn_emulation_sysctl(void) sysctl->maxlen = sizeof(int); sysctl->procname = insn->ops->name; - sysctl->data = insn; + sysctl->data = &insn->current_mode; sysctl->extra1 = &insn->min; sysctl->extra2 = &insn->max; sysctl->proc_handler = emulation_proc_handler; -- 2.35.1