From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754578AbdASUfN (ORCPT ); Thu, 19 Jan 2017 15:35:13 -0500 Received: from mail-io0-f175.google.com ([209.85.223.175]:33606 "EHLO mail-io0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754172AbdASUfK (ORCPT ); Thu, 19 Jan 2017 15:35:10 -0500 MIME-Version: 1.0 In-Reply-To: <20170105224249.GA50925@beast> References: <20170105224249.GA50925@beast> From: Kees Cook Date: Thu, 19 Jan 2017 12:35:07 -0800 X-Google-Sender-Auth: JqxW7LfY-LuMdkQKQqp81whuwhI Message-ID: Subject: Re: [PATCH] fbdev: color map copying bounds checking To: Andrew Morton Cc: LKML , linux-fbdev@vger.kernel.org, Min Chong , Dan Carpenter , Tomi Valkeinen Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi again, It's been two weeks with no response. This fixes a kernel heap OOB read. Andrew, can you take this into -mm? -Kees On Thu, Jan 5, 2017 at 2:42 PM, Kees Cook wrote: > Copying color maps to userspace doesn't check the value of to->start, > which will cause kernel heap buffer OOB read due to signedness wraps. > > CVE-2016-8405 > > Reported-by: Peter Pi (@heisecode) of Trend Micro > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > Cc: stable@vger.kernel.org > Signed-off-by: Kees Cook > --- > drivers/video/fbdev/core/fbcmap.c | 26 ++++++++++++++------------ > 1 file changed, 14 insertions(+), 12 deletions(-) > > diff --git a/drivers/video/fbdev/core/fbcmap.c b/drivers/video/fbdev/core/fbcmap.c > index f89245b8ba8e..68a113594808 100644 > --- a/drivers/video/fbdev/core/fbcmap.c > +++ b/drivers/video/fbdev/core/fbcmap.c > @@ -163,17 +163,18 @@ void fb_dealloc_cmap(struct fb_cmap *cmap) > > int fb_copy_cmap(const struct fb_cmap *from, struct fb_cmap *to) > { > - int tooff = 0, fromoff = 0; > - int size; > + unsigned int tooff = 0, fromoff = 0; > + size_t size; > > if (to->start > from->start) > fromoff = to->start - from->start; > else > tooff = from->start - to->start; > - size = to->len - tooff; > - if (size > (int) (from->len - fromoff)) > - size = from->len - fromoff; > - if (size <= 0) > + if (fromoff >= from->len || tooff >= to->len) > + return -EINVAL; > + > + size = min_t(size_t, to->len - tooff, from->len - fromoff); > + if (size == 0) > return -EINVAL; > size *= sizeof(u16); > > @@ -187,17 +188,18 @@ int fb_copy_cmap(const struct fb_cmap *from, struct fb_cmap *to) > > int fb_cmap_to_user(const struct fb_cmap *from, struct fb_cmap_user *to) > { > - int tooff = 0, fromoff = 0; > - int size; > + unsigned int tooff = 0, fromoff = 0; > + size_t size; > > if (to->start > from->start) > fromoff = to->start - from->start; > else > tooff = from->start - to->start; > - size = to->len - tooff; > - if (size > (int) (from->len - fromoff)) > - size = from->len - fromoff; > - if (size <= 0) > + if (fromoff >= from->len || tooff >= to->len) > + return -EINVAL; > + > + size = min_t(size_t, to->len - tooff, from->len - fromoff); > + if (size == 0) > return -EINVAL; > size *= sizeof(u16); > > -- > 2.7.4 > > > -- > Kees Cook > Nexus Security -- Kees Cook Nexus Security From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kees Cook Date: Thu, 19 Jan 2017 20:35:07 +0000 Subject: Re: [PATCH] fbdev: color map copying bounds checking Message-Id: List-Id: References: <20170105224249.GA50925@beast> In-Reply-To: <20170105224249.GA50925@beast> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Andrew Morton Cc: LKML , linux-fbdev@vger.kernel.org, Min Chong , Dan Carpenter , Tomi Valkeinen Hi again, It's been two weeks with no response. This fixes a kernel heap OOB read. Andrew, can you take this into -mm? -Kees On Thu, Jan 5, 2017 at 2:42 PM, Kees Cook wrote: > Copying color maps to userspace doesn't check the value of to->start, > which will cause kernel heap buffer OOB read due to signedness wraps. > > CVE-2016-8405 > > Reported-by: Peter Pi (@heisecode) of Trend Micro > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > Cc: stable@vger.kernel.org > Signed-off-by: Kees Cook > --- > drivers/video/fbdev/core/fbcmap.c | 26 ++++++++++++++------------ > 1 file changed, 14 insertions(+), 12 deletions(-) > > diff --git a/drivers/video/fbdev/core/fbcmap.c b/drivers/video/fbdev/core/fbcmap.c > index f89245b8ba8e..68a113594808 100644 > --- a/drivers/video/fbdev/core/fbcmap.c > +++ b/drivers/video/fbdev/core/fbcmap.c > @@ -163,17 +163,18 @@ void fb_dealloc_cmap(struct fb_cmap *cmap) > > int fb_copy_cmap(const struct fb_cmap *from, struct fb_cmap *to) > { > - int tooff = 0, fromoff = 0; > - int size; > + unsigned int tooff = 0, fromoff = 0; > + size_t size; > > if (to->start > from->start) > fromoff = to->start - from->start; > else > tooff = from->start - to->start; > - size = to->len - tooff; > - if (size > (int) (from->len - fromoff)) > - size = from->len - fromoff; > - if (size <= 0) > + if (fromoff >= from->len || tooff >= to->len) > + return -EINVAL; > + > + size = min_t(size_t, to->len - tooff, from->len - fromoff); > + if (size = 0) > return -EINVAL; > size *= sizeof(u16); > > @@ -187,17 +188,18 @@ int fb_copy_cmap(const struct fb_cmap *from, struct fb_cmap *to) > > int fb_cmap_to_user(const struct fb_cmap *from, struct fb_cmap_user *to) > { > - int tooff = 0, fromoff = 0; > - int size; > + unsigned int tooff = 0, fromoff = 0; > + size_t size; > > if (to->start > from->start) > fromoff = to->start - from->start; > else > tooff = from->start - to->start; > - size = to->len - tooff; > - if (size > (int) (from->len - fromoff)) > - size = from->len - fromoff; > - if (size <= 0) > + if (fromoff >= from->len || tooff >= to->len) > + return -EINVAL; > + > + size = min_t(size_t, to->len - tooff, from->len - fromoff); > + if (size = 0) > return -EINVAL; > size *= sizeof(u16); > > -- > 2.7.4 > > > -- > Kees Cook > Nexus Security -- Kees Cook Nexus Security