Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753591Ab2JZAtt (ORCPT ); Thu, 25 Oct 2012 20:49:49 -0400 Received: from mail.kernel.org ([198.145.19.201]:52416 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752764Ab2JZAFm (ORCPT ); Thu, 25 Oct 2012 20:05:42 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , alan@lxorguk.ukuu.org.uk, PaX Team , Kees Cook , Andi Kleen , Brad Spengler , Andrew Morton , Linus Torvalds Subject: [ 07/31] kernel/sys.c: fix stack memory content leak via UNAME26 Date: Thu, 25 Oct 2012 17:04:14 -0700 Message-Id: <20121026000215.707218452@linuxfoundation.org> X-Mailer: git-send-email 1.7.12.2.421.g261b511 In-Reply-To: <20121026000214.941721299@linuxfoundation.org> References: <20121026000214.941721299@linuxfoundation.org> User-Agent: quilt/0.60-2.1.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2229 Lines: 69 3.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kees Cook commit 2702b1526c7278c4d65d78de209a465d4de2885e upstream. Calling uname() with the UNAME26 personality set allows a leak of kernel stack contents. This fixes it by defensively calculating the length of copy_to_user() call, making the len argument unsigned, and initializing the stack buffer to zero (now technically unneeded, but hey, overkill). CVE-2012-0957 Reported-by: PaX Team Signed-off-by: Kees Cook Cc: Andi Kleen Cc: PaX Team Cc: Brad Spengler Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- kernel/sys.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1133,15 +1133,16 @@ DECLARE_RWSEM(uts_sem); * Work around broken programs that cannot handle "Linux 3.0". * Instead we map 3.x to 2.6.40+x, so e.g. 3.0 would be 2.6.40 */ -static int override_release(char __user *release, int len) +static int override_release(char __user *release, size_t len) { int ret = 0; - char buf[65]; if (current->personality & UNAME26) { - char *rest = UTS_RELEASE; + const char *rest = UTS_RELEASE; + char buf[65] = { 0 }; int ndots = 0; unsigned v; + size_t copy; while (*rest) { if (*rest == '.' && ++ndots >= 3) @@ -1151,8 +1152,9 @@ static int override_release(char __user rest++; } v = ((LINUX_VERSION_CODE >> 8) & 0xff) + 40; - snprintf(buf, len, "2.6.%u%s", v, rest); - ret = copy_to_user(release, buf, len); + copy = min(sizeof(buf), max_t(size_t, 1, len)); + copy = scnprintf(buf, copy, "2.6.%u%s", v, rest); + ret = copy_to_user(release, buf, copy + 1); } return ret; } -- 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/