From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933905AbdKAVVi (ORCPT ); Wed, 1 Nov 2017 17:21:38 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:35063 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933659AbdKAVVd (ORCPT ); Wed, 1 Nov 2017 17:21:33 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Eric Biggers , David Howells , James Morris , Willy Tarreau Subject: [PATCH 3.10 023/139] KEYS: fix dereferencing NULL payload with nonzero length Date: Wed, 1 Nov 2017 22:17:23 +0100 Message-Id: <1509571159-4405-24-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1509571159-4405-1-git-send-email-w@1wt.eu> References: <1509571159-4405-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Biggers commit 5649645d725c73df4302428ee4e02c869248b4c5 upstream. sys_add_key() and the KEYCTL_UPDATE operation of sys_keyctl() allowed a NULL payload with nonzero length to be passed to the key type's ->preparse(), ->instantiate(), and/or ->update() methods. Various key types including asymmetric, cifs.idmap, cifs.spnego, and pkcs7_test did not handle this case, allowing an unprivileged user to trivially cause a NULL pointer dereference (kernel oops) if one of these key types was present. Fix it by doing the copy_from_user() when 'plen' is nonzero rather than when '_payload' is non-NULL, causing the syscall to fail with EFAULT as expected when an invalid buffer is specified. Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers Signed-off-by: David Howells Signed-off-by: James Morris Signed-off-by: Willy Tarreau --- security/keys/keyctl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index 066baa1..7576f49 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -93,7 +93,7 @@ SYSCALL_DEFINE5(add_key, const char __user *, _type, payload = NULL; vm = false; - if (_payload) { + if (plen) { ret = -ENOMEM; payload = kmalloc(plen, GFP_KERNEL | __GFP_NOWARN); if (!payload) { @@ -327,7 +327,7 @@ long keyctl_update_key(key_serial_t id, /* pull the payload in if one was supplied */ payload = NULL; - if (_payload) { + if (plen) { ret = -ENOMEM; payload = kmalloc(plen, GFP_KERNEL); if (!payload) -- 2.8.0.rc2.1.gbe9624a