From patchwork Sun Dec 17 23:53:31 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Tobin C. Harding" X-Patchwork-Id: 849730 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=tobin.cc header.i=@tobin.cc header.b="KEiWxmN3"; dkim=pass (2048-bit key; unprotected) header.d=messagingengine.com header.i=@messagingengine.com header.b="pSMsRonQ"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3z0Lck2jyGz9sDB for ; Mon, 18 Dec 2017 10:54:46 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757691AbdLQXyd (ORCPT ); Sun, 17 Dec 2017 18:54:33 -0500 Received: from out3-smtp.messagingengine.com ([66.111.4.27]:34021 "EHLO out3-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757622AbdLQXxz (ORCPT ); Sun, 17 Dec 2017 18:53:55 -0500 Received: from compute5.internal (compute5.nyi.internal [10.202.2.45]) by mailout.nyi.internal (Postfix) with ESMTP id 877D520DA4; Sun, 17 Dec 2017 18:53:54 -0500 (EST) Received: from frontend1 ([10.202.2.160]) by compute5.internal (MEProxy); Sun, 17 Dec 2017 18:53:54 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tobin.cc; h=cc :date:from:in-reply-to:message-id:references:subject:to :x-me-sender:x-me-sender:x-sasl-enc; s=fm1; bh=W0/70Jt4wydvsPrPr XT/qT3HtkhWHysmgMbFTm17vlo=; b=KEiWxmN3ocZUKn7TJAOxkkZdNLM9J8EJh oR4Wx6bi2+vYofJII1h+JZvhcmK020XPdT1/oAg4QGeL8gEpqnBdNEOu5AytdKhD o4LfMLiuzn/JZZ263ON8aL3qrNmOVgxOSk4a3guRdTWPYqK2WvadJUrPrqYxj8fC G7iZ7WUPXm90wVWn0npFj/FJCiC0Uqh+AAQ5ewZnbH6cw3JsC4/wkjcA2SDuiE1j zB6ZgC+fk6EboRcjM7iPvgEnytokVOauaCPmr7EScrytp6OLDDvWChaf/K9DyGg+ BCsBWJEZzf0nCk8DSF7A0C7V4GOZDXlpPCNhNJv3HHCDphRdIvIFQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:date:from:in-reply-to:message-id :references:subject:to:x-me-sender:x-me-sender:x-sasl-enc; s= fm1; bh=W0/70Jt4wydvsPrPrXT/qT3HtkhWHysmgMbFTm17vlo=; b=pSMsRonQ ojyZmhDx8bShVyrLOWRK3z+fWAZzv9y4SbykE5BXxciR616F/D0CtSNPA08oMEYI b1345pjWNWNMZdNfMyKY4/C8rC7IKw9+PQEIzkENEqlBWr+UlVGuXshLbQybvgS+ 204EWFAA0yY0mQcMs9UC6FzEgTp/G/f6MSJUxnMr1ECS0lc1+vFO1hNnGDs8/B8u rRLQIlirt/i1DIagXDOKimjRLqsmROG8xLell6GHIfL5e1ASrTOAoQneMSPadqIi aRKLWr2utVvOY5+L06ABkQdVJfk0v+R8eqpZ13tD9kvDg4Lqh8XLRnD8hg1ayiDL 8b3oLiH4n16MIw== X-ME-Sender: Received: from localhost (unknown [124.170.221.129]) by mail.messagingengine.com (Postfix) with ESMTPA id CECE37E497; Sun, 17 Dec 2017 18:53:53 -0500 (EST) From: "Tobin C. Harding" To: kernel-hardening@lists.openwall.com Cc: "Tobin C. Harding" , Steven Rostedt , Tycho Andersen , Linus Torvalds , Kees Cook , Andrew Morton , Daniel Borkmann , Masahiro Yamada , Alexei Starovoitov , linux-kernel@vger.kernel.org, Network Development Subject: [PATCH 2/3] vsprintf: print if symbol not found Date: Mon, 18 Dec 2017 10:53:31 +1100 Message-Id: <1513554812-13014-3-git-send-email-me@tobin.cc> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1513554812-13014-1-git-send-email-me@tobin.cc> References: <1513554812-13014-1-git-send-email-me@tobin.cc> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Depends on: commit bd6b239cdbb2 ("kallsyms: don't leak address when symbol not found") Currently vsprintf for specifiers %p[SsB] relies on the behaviour of kallsyms (sprint_symbol()) and prints the actual address if a symbol is not found. Previous patch changes this behaviour so tha sprint_symbol() returns an error if symbol not found. With this patch in place we can print a sanitized message '' instead of leaking the address. Print '' for printk specifier %s[sSB] if no symbol is found. Signed-off-by: Tobin C. Harding --- include/linux/kernel.h | 2 ++ lib/vsprintf.c | 18 +++++++++++++++--- 2 files changed, 17 insertions(+), 3 deletions(-) diff --git a/include/linux/kernel.h b/include/linux/kernel.h index ce51455e2adf..89e8ce79c2d1 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -460,6 +460,8 @@ char *kvasprintf(gfp_t gfp, const char *fmt, va_list args); extern __printf(2, 0) const char *kvasprintf_const(gfp_t gfp, const char *fmt, va_list args); +extern int string_is_no_symbol(const char *s); + extern __scanf(2, 3) int sscanf(const char *, const char *, ...); extern __scanf(2, 0) diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 01c3957b2de6..c112b0980ead 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -667,6 +667,8 @@ char *bdev_name(char *buf, char *end, struct block_device *bdev, } #endif +#define PRINTK_NO_SYMBOL_STR "" + static noinline_for_stack char *symbol_string(char *buf, char *end, void *ptr, struct printf_spec spec, const char *fmt) @@ -674,6 +676,7 @@ char *symbol_string(char *buf, char *end, void *ptr, unsigned long value; #ifdef CONFIG_KALLSYMS char sym[KSYM_SYMBOL_LEN]; + int ret; #endif if (fmt[1] == 'R') @@ -682,11 +685,14 @@ char *symbol_string(char *buf, char *end, void *ptr, #ifdef CONFIG_KALLSYMS if (*fmt == 'B') - sprint_backtrace(sym, value); + ret = sprint_backtrace(sym, value); else if (*fmt != 'f' && *fmt != 's') - sprint_symbol(sym, value); + ret = sprint_symbol(sym, value); else - sprint_symbol_no_offset(sym, value); + ret = sprint_symbol_no_offset(sym, value); + + if (ret == -1) + strcpy(sym, PRINTK_NO_SYMBOL_STR); return string(buf, end, sym, spec); #else @@ -694,6 +700,12 @@ char *symbol_string(char *buf, char *end, void *ptr, #endif } +int string_is_no_symbol(const char *s) +{ + return !!strstr(s, PRINTK_NO_SYMBOL_STR); +} +EXPORT_SYMBOL(string_is_no_symbol); + static noinline_for_stack char *resource_string(char *buf, char *end, struct resource *res, struct printf_spec spec, const char *fmt)