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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 61F26C606C1 for ; Mon, 8 Jul 2019 15:33:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2D5EE2177B for ; Mon, 8 Jul 2019 15:33:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562599981; bh=IkOI15sZZlOyTX2gplV9VjqNzTdKT5VA2EfxMc9bQ4A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=0OptxMwoFNY4L0TlNTrxjpU/BPHE5swrPTPHh+PBv8WF9yNJzp/uSc0qr5RdKc3zn fr657p3ZDohVTUoYMAA1MnQdLZqdxmD9z24e4qR2W33idK6MYVqgcGMhzUe9N7omJM yPZVYbquZDbqpNbIKpdzXofUOLjDYKhj+McEvv1Q= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390246AbfGHPdA (ORCPT ); Mon, 8 Jul 2019 11:33:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:34888 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390231AbfGHPc6 (ORCPT ); Mon, 8 Jul 2019 11:32:58 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B7385216F4; Mon, 8 Jul 2019 15:32:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562599977; bh=IkOI15sZZlOyTX2gplV9VjqNzTdKT5VA2EfxMc9bQ4A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Z/w6+3jrQyuT32zjfbpDsywIojpXfTCXkeQzjpJR/iCYfNxkCCtnoPVmDYuFQcrf8 a7ch6533PoQ3HAbfTnYV9y+T58mtBCsFUji/YAu1yGglseXnQNsxMIia4+VHisKH2a dbwgvPsCpJrkNl5+QpgmYwLnHuIjlIOG/0/4QjHE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Johannes Erdfelt , Jessica Yu , Petr Mladek , Miroslav Benes , Josh Poimboeuf , "Steven Rostedt (VMware)" , Sasha Levin Subject: [PATCH 5.1 54/96] module: Fix livepatch/ftrace module text permissions race Date: Mon, 8 Jul 2019 17:13:26 +0200 Message-Id: <20190708150529.430353583@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190708150526.234572443@linuxfoundation.org> References: <20190708150526.234572443@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [ Upstream commit 9f255b632bf12c4dd7fc31caee89aa991ef75176 ] It's possible for livepatch and ftrace to be toggling a module's text permissions at the same time, resulting in the following panic: BUG: unable to handle page fault for address: ffffffffc005b1d9 #PF: supervisor write access in kernel mode #PF: error_code(0x0003) - permissions violation PGD 3ea0c067 P4D 3ea0c067 PUD 3ea0e067 PMD 3cc13067 PTE 3b8a1061 Oops: 0003 [#1] PREEMPT SMP PTI CPU: 1 PID: 453 Comm: insmod Tainted: G O K 5.2.0-rc1-a188339ca5 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-20181126_142135-anatol 04/01/2014 RIP: 0010:apply_relocate_add+0xbe/0x14c Code: fa 0b 74 21 48 83 fa 18 74 38 48 83 fa 0a 75 40 eb 08 48 83 38 00 74 33 eb 53 83 38 00 75 4e 89 08 89 c8 eb 0a 83 38 00 75 43 <89> 08 48 63 c1 48 39 c8 74 2e eb 48 83 38 00 75 32 48 29 c1 89 08 RSP: 0018:ffffb223c00dbb10 EFLAGS: 00010246 RAX: ffffffffc005b1d9 RBX: 0000000000000000 RCX: ffffffff8b200060 RDX: 000000000000000b RSI: 0000004b0000000b RDI: ffff96bdfcd33000 RBP: ffffb223c00dbb38 R08: ffffffffc005d040 R09: ffffffffc005c1f0 R10: ffff96bdfcd33c40 R11: ffff96bdfcd33b80 R12: 0000000000000018 R13: ffffffffc005c1f0 R14: ffffffffc005e708 R15: ffffffff8b2fbc74 FS: 00007f5f447beba8(0000) GS:ffff96bdff900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffc005b1d9 CR3: 000000003cedc002 CR4: 0000000000360ea0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: klp_init_object_loaded+0x10f/0x219 ? preempt_latency_start+0x21/0x57 klp_enable_patch+0x662/0x809 ? virt_to_head_page+0x3a/0x3c ? kfree+0x8c/0x126 patch_init+0x2ed/0x1000 [livepatch_test02] ? 0xffffffffc0060000 do_one_initcall+0x9f/0x1c5 ? kmem_cache_alloc_trace+0xc4/0xd4 ? do_init_module+0x27/0x210 do_init_module+0x5f/0x210 load_module+0x1c41/0x2290 ? fsnotify_path+0x3b/0x42 ? strstarts+0x2b/0x2b ? kernel_read+0x58/0x65 __do_sys_finit_module+0x9f/0xc3 ? __do_sys_finit_module+0x9f/0xc3 __x64_sys_finit_module+0x1a/0x1c do_syscall_64+0x52/0x61 entry_SYSCALL_64_after_hwframe+0x44/0xa9 The above panic occurs when loading two modules at the same time with ftrace enabled, where at least one of the modules is a livepatch module: CPU0 CPU1 klp_enable_patch() klp_init_object_loaded() module_disable_ro() ftrace_module_enable() ftrace_arch_code_modify_post_process() set_all_modules_text_ro() klp_write_object_relocations() apply_relocate_add() *patches read-only code* - BOOM A similar race exists when toggling ftrace while loading a livepatch module. Fix it by ensuring that the livepatch and ftrace code patching operations -- and their respective permissions changes -- are protected by the text_mutex. Link: http://lkml.kernel.org/r/ab43d56ab909469ac5d2520c5d944ad6d4abd476.1560474114.git.jpoimboe@redhat.com Reported-by: Johannes Erdfelt Fixes: 444d13ff10fb ("modules: add ro_after_init support") Acked-by: Jessica Yu Reviewed-by: Petr Mladek Reviewed-by: Miroslav Benes Signed-off-by: Josh Poimboeuf Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Sasha Levin --- kernel/livepatch/core.c | 6 ++++++ kernel/trace/ftrace.c | 10 +++++++++- 2 files changed, 15 insertions(+), 1 deletion(-) diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index eb0ee10a1981..05d5b0afc864 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -30,6 +30,7 @@ #include #include #include +#include #include #include "core.h" #include "patch.h" @@ -746,16 +747,21 @@ static int klp_init_object_loaded(struct klp_patch *patch, struct klp_func *func; int ret; + mutex_lock(&text_mutex); + module_disable_ro(patch->mod); ret = klp_write_object_relocations(patch->mod, obj); if (ret) { module_enable_ro(patch->mod, true); + mutex_unlock(&text_mutex); return ret; } arch_klp_init_object_loaded(patch, obj); module_enable_ro(patch->mod, true); + mutex_unlock(&text_mutex); + klp_for_each_func(obj, func) { ret = klp_find_object_symbol(obj->name, func->old_name, func->old_sympos, diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 538f0b1c7ea2..045e7f46a74a 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -34,6 +34,7 @@ #include #include #include +#include #include @@ -2614,10 +2615,12 @@ static void ftrace_run_update_code(int command) { int ret; + mutex_lock(&text_mutex); + ret = ftrace_arch_code_modify_prepare(); FTRACE_WARN_ON(ret); if (ret) - return; + goto out_unlock; /* * By default we use stop_machine() to modify the code. @@ -2629,6 +2632,9 @@ static void ftrace_run_update_code(int command) ret = ftrace_arch_code_modify_post_process(); FTRACE_WARN_ON(ret); + +out_unlock: + mutex_unlock(&text_mutex); } static void ftrace_run_modify_code(struct ftrace_ops *ops, int command, @@ -5779,6 +5785,7 @@ void ftrace_module_enable(struct module *mod) struct ftrace_page *pg; mutex_lock(&ftrace_lock); + mutex_lock(&text_mutex); if (ftrace_disabled) goto out_unlock; @@ -5840,6 +5847,7 @@ void ftrace_module_enable(struct module *mod) ftrace_arch_code_modify_post_process(); out_unlock: + mutex_unlock(&text_mutex); mutex_unlock(&ftrace_lock); process_cached_mods(mod->name); -- 2.20.1