From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Rosenberg Subject: [PATCH] irda: prevent integer underflow in IRLMP_ENUMDEVICES Date: Wed, 22 Dec 2010 18:58:27 -0500 Message-ID: <1293062307.9820.331.camel@dan> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, security@kernel.org To: samuel@sortiz.org, davem@davemloft.net Return-path: Received: from mx1.vsecurity.com ([209.67.252.12]:51215 "EHLO mx1.vsecurity.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752974Ab0LVX6b (ORCPT ); Wed, 22 Dec 2010 18:58:31 -0500 Sender: netdev-owner@vger.kernel.org List-ID: If the user-provided len is less than the expected offset, the IRLMP_ENUMDEVICES getsockopt will do a copy_to_user() with a very large size value. While this isn't be a security issue on x86 because it will get caught by the access_ok() check, it may leak large amounts of kernel heap on other architectures. In any event, this patch fixes it. Signed-off-by: Dan Rosenberg Cc: stable --- net/irda/af_irda.c | 18 +++++++++++------- 1 files changed, 11 insertions(+), 7 deletions(-) diff --git a/net/irda/af_irda.c b/net/irda/af_irda.c index a6de305..241d7a0 100644 --- a/net/irda/af_irda.c +++ b/net/irda/af_irda.c @@ -2280,6 +2280,16 @@ static int irda_getsockopt(struct socket *sock, int level, int optname, switch (optname) { case IRLMP_ENUMDEVICES: + + /* Offset to first device entry */ + offset = sizeof(struct irda_device_list) - + sizeof(struct irda_device_info); + + if (len < offset) { + err = -EINVAL; + goto out; + } + /* Ask lmp for the current discovery log */ discoveries = irlmp_get_discoveries(&list.len, self->mask.word, self->nslots); @@ -2290,15 +2300,9 @@ static int irda_getsockopt(struct socket *sock, int level, int optname, } /* Write total list length back to client */ - if (copy_to_user(optval, &list, - sizeof(struct irda_device_list) - - sizeof(struct irda_device_info))) + if (copy_to_user(optval, &list, offset)) err = -EFAULT; - /* Offset to first device entry */ - offset = sizeof(struct irda_device_list) - - sizeof(struct irda_device_info); - /* Copy the list itself - watch for overflow */ if (list.len > 2048) { err = -EINVAL;