Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752736AbdFHAKy (ORCPT ); Wed, 7 Jun 2017 20:10:54 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:50123 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752070AbdFGXCM (ORCPT ); Wed, 7 Jun 2017 19:02:12 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Kees Cook , Min Chong , Dan Carpenter , Tomi Valkeinen , Bartlomiej Zolnierkiewicz , Andrew Morton , Linus Torvalds , Willy Tarreau Subject: [PATCH 3.10 009/250] fbdev: color map copying bounds checking Date: Thu, 8 Jun 2017 00:56:35 +0200 Message-Id: <1496876436-32402-10-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1496876436-32402-1-git-send-email-w@1wt.eu> References: <1496876436-32402-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2418 Lines: 80 From: Kees Cook commit 2dc705a9930b4806250fbf5a76e55266e59389f2 upstream. 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 Link: http://lkml.kernel.org/r/20170105224249.GA50925@beast Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kees Cook Reported-by: Peter Pi (@heisecode) of Trend Micro Cc: Min Chong Cc: Dan Carpenter Cc: Tomi Valkeinen Cc: Bartlomiej Zolnierkiewicz Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Willy Tarreau --- drivers/video/fbcmap.c | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-) diff --git a/drivers/video/fbcmap.c b/drivers/video/fbcmap.c index 5c3960d..71666c0 100644 --- a/drivers/video/fbcmap.c +++ b/drivers/video/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); -- 2.8.0.rc2.1.gbe9624a