Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753521AbbFAPsv (ORCPT ); Mon, 1 Jun 2015 11:48:51 -0400 Received: from cantor2.suse.de ([195.135.220.15]:35193 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751447AbbFAPsn (ORCPT ); Mon, 1 Jun 2015 11:48:43 -0400 From: Miroslav Benes To: jpoimboe@redhat.com, sjenning@redhat.com, jkosina@suse.cz, vojtech@suse.cz Cc: live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, pmladek@suse.cz, Miroslav Benes Subject: [PATCH] livepatch: add module locking around kallsyms calls Date: Mon, 1 Jun 2015 17:48:37 +0200 Message-Id: <1433173717-20885-1-git-send-email-mbenes@suse.cz> X-Mailer: git-send-email 2.1.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1922 Lines: 61 The list of loaded modules is walked through in module_kallsyms_on_each_symbol (called by kallsyms_on_each_symbol). The module_mutex lock should be acquired to prevent potential corruptions in the list. This was uncovered with new lockdep asserts in module code introduced by the commit 0be964be0d45 ("module: Sanitize RCU usage and locking") in recent next- trees. Signed-off-by: Miroslav Benes --- kernel/livepatch/core.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index e6c8d54..c40ebcc 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -179,7 +179,9 @@ static int klp_find_object_symbol(const char *objname, const char *name, .count = 0 }; + mutex_lock(&module_mutex); kallsyms_on_each_symbol(klp_find_callback, &args); + mutex_unlock(&module_mutex); if (args.count == 0) pr_err("symbol '%s' not found in symbol table\n", name); @@ -219,13 +221,19 @@ static int klp_verify_vmlinux_symbol(const char *name, unsigned long addr) .name = name, .addr = addr, }; + int ret; - if (kallsyms_on_each_symbol(klp_verify_callback, &args)) - return 0; + mutex_lock(&module_mutex); + ret = kallsyms_on_each_symbol(klp_verify_callback, &args); + mutex_unlock(&module_mutex); - pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?\n", - name, addr); - return -EINVAL; + if (!ret) { + pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?\n", + name, addr); + return -EINVAL; + } + + return 0; } static int klp_find_verify_func_addr(struct klp_object *obj, -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/