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 BAE3DC19F2A for ; Mon, 8 Aug 2022 01:59:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243963AbiHHB75 (ORCPT ); Sun, 7 Aug 2022 21:59:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52302 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243970AbiHHB4n (ORCPT ); Sun, 7 Aug 2022 21:56:43 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 724D91CFDA; Sun, 7 Aug 2022 18:40:09 -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 EBC2B60EE6; Mon, 8 Aug 2022 01:40:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 253E6C433C1; Mon, 8 Aug 2022 01:40:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659922808; bh=36mSMLfv648ocAbMyXAwIO6WQKD5SBFkJ4sGOVKXnYg=; h=From:To:Cc:Subject:Date:From; b=ZlmbI3vtkM48FJyix42lpJbM6r9MoIyttD9w+yGPoEcIKw+mgag4k34G1X/8w5B1v E/wAmuEtSoZc09v/PXHNQekuDmHtJ9R++e7gSAZNwuyKVfknX7U2ZBE57m+lWb5eGu SEKOuIgPvSViXbwzOVW50g5IVWz2gmUu0DqHW4uUxWqaMJLaYEJ/T4gA1M2wqxLoLf LxTLOVvhDE81htOjxEUtm1194H0YxrEZSXsXyqiSXxdjnL6z+Qeudh/Aet4HLFo7sM TpiIhGdEE+08TgNzJesSTAF77lJDNYD6wk0T911gTrLTshnKe4vSUMyIYvrbZD0STF ulkE5YXmVQmdg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: =?UTF-8?q?haibinzhang=20=28=E5=BC=A0=E6=B5=B7=E6=96=8C=29?= , hewenliang , Catalin Marinas , Will Deacon , Sasha Levin , ardb@kernel.org, mark.rutland@arm.com, linux-arm-kernel@lists.infradead.org Subject: [PATCH AUTOSEL 4.9 1/8] arm64: fix oops in concurrently setting insn_emulation sysctls Date: Sun, 7 Aug 2022 21:39:56 -0400 Message-Id: <20220808014005.317064-1-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore 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 49989207989a..89946ed1adb9 100644 --- a/arch/arm64/kernel/armv8_deprecated.c +++ b/arch/arm64/kernel/armv8_deprecated.c @@ -64,6 +64,7 @@ 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) { @@ -209,10 +210,10 @@ 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) @@ -225,7 +226,7 @@ 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; } @@ -255,7 +256,7 @@ static void __init register_insn_emulation_sysctl(struct ctl_table *table) 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