From patchwork Wed Apr 10 19:08:22 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 10894539 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7063617E0 for ; Wed, 10 Apr 2019 19:09:00 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5C52128B91 for ; Wed, 10 Apr 2019 19:09:00 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4FF4328B8E; Wed, 10 Apr 2019 19:09:00 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 7A52A28B8E for ; Wed, 10 Apr 2019 19:08:59 +0000 (UTC) Received: (qmail 29864 invoked by uid 550); 10 Apr 2019 19:08:53 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 29803 invoked from network); 10 Apr 2019 19:08:52 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=l1Qx3/w7WRcsYn9eaUPF4C/V6e/ThCB6vwEWsBbRAUs=; b=K1niSa9XrmXDprUUjfMYdOBFSp2971yq6KfPCwZQB8zLkTG1hoq4Be1dObMgZbLp0D FgA32CQNknYoP/LwUlvsogre3kTd77MjYHx13oD0Jew4VYRShWVM/pJBSYocrrntdmAu D1sXx3I/JxMC9QxZQlnvOYUI8RX8F/VfgZzSg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=l1Qx3/w7WRcsYn9eaUPF4C/V6e/ThCB6vwEWsBbRAUs=; b=JgxecCxVgx16o5GtwrqUyvV9c/eL0uJWzdFg1hmBUx/1G/3HuXyyxrUM5YTaeMcgdM dcEIunYxn08/lHzrh/xlo3wbzKAMTC1ygcaGfD9MbZgX1Z+JyWYuNlXpWNsZBpy8AFuk hWEAatWU0gGXJNSPhqD8XZcU8ODhlmmVDkaKlNCX3zMPBF0gcKc1ecLt5glmhgHOgAdm VsrjlADJta/LMnINaoDPNDHhJWQsKfzFkWhbOI5q1cN5JjLWMY3hc5zvDFGR3p4WyS9w 0pBhd9Yqs8pSCI3JAeZp0k/wE7/OMcnldey0D0JliE8OYMp6wVz1Zsz6wJgUGUYwNVkO LU9w== X-Gm-Message-State: APjAAAWaGvvXg5dH1VzRs03VmG3x/bKwN1hDIVilxppmcowsS0GrCMp8 QFP0SI7WO21WXl2GZwINaL8ToQ== X-Google-Smtp-Source: APXvYqz+MW7nlOFWhyh3M8V1FDWmZWoua6y9RzTsKCv7M5lQ1B8chUn0jXM05TM41vfWXGVzHTm4EQ== X-Received: by 2002:a62:e304:: with SMTP id g4mr39107478pfh.71.1554923320781; Wed, 10 Apr 2019 12:08:40 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org Cc: "Joel Fernandes (Google)" , paulmck@linux.vnet.ibm.com, keescook@chromium.org, Jessica Yu , kernel-hardening@lists.openwall.com, kernel-team@android.com, mathieu.desnoyers@efficios.com, rcu@vger.kernel.org, rostedt@goodmis.org Subject: [PATCH v2 2/3] module: Make srcu_struct ptr array as read-only post init Date: Wed, 10 Apr 2019 15:08:22 -0400 Message-Id: <20190410190823.109172-2-joel@joelfernandes.org> X-Mailer: git-send-email 2.21.0.392.gf8f6787159e-goog In-Reply-To: <20190410190823.109172-1-joel@joelfernandes.org> References: <20190410190823.109172-1-joel@joelfernandes.org> MIME-Version: 1.0 X-Virus-Scanned: ClamAV using ClamSMTP Since commit title ("srcu: Allocate per-CPU data for DEFINE_SRCU() in modules"), modules that call DEFINE_{STATIC,}SRCU will have a new array of srcu_struct pointers which is used by srcu code to initialize and clean up these structures. There is no reason for this array of pointers to be writable, and can cause security or other hidden bugs. Mark these are read-only after the module init has completed. Suggested-by: paulmck@linux.vnet.ibm.com Suggested-by: keescook@chromium.org Acked-by: keescook@chromium.org Signed-off-by: Joel Fernandes (Google) --- kernel/module.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index 1acddb93282a..8b9631e789f0 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -3305,7 +3305,7 @@ core_param(module_blacklist, module_blacklist, charp, 0400); * layout_sections() can put it in the right place. * Note: ro_after_init sections also have SHF_{WRITE,ALLOC} set. */ -static char *ro_after_init_sections[] = { +static const char * const ro_after_init_sections[] = { ".data..ro_after_init", /* @@ -3314,6 +3314,12 @@ static char *ro_after_init_sections[] = { * annotated as such at module load time. */ "__jump_table", + + /* + * Used for SRCU structures which need to be initialized/cleaned up + * by the SRCU notifiers + */ + "___srcu_struct_ptrs", }; static struct module *layout_and_allocate(struct load_info *info, int flags) @@ -3336,7 +3342,7 @@ static struct module *layout_and_allocate(struct load_info *info, int flags) info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC; /* Set sh_flags for read-only after init sections */ - for (i = 0; ro_after_init_sections[i]; i++) { + for (i = 0; i < ARRAY_SIZE(ro_after_init_sections); i++) { ndx = find_sec(info, ro_after_init_sections[i]); if (ndx) info->sechdrs[ndx].sh_flags |= SHF_RO_AFTER_INIT;