From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Carpenter Date: Tue, 29 Oct 2019 18:23:20 +0000 Subject: [PATCH] fbdev: potential information leak in do_fb_ioctl() Message-Id: <20191029182320.GA17569@mwanda> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Bartlomiej Zolnierkiewicz , Andrea Righi Cc: linux-fbdev@vger.kernel.org, security@kernel.org, Kees Cook , kernel-janitors@vger.kernel.org, Daniel Vetter , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Julia Lawall , Gerd Hoffmann , Sam Ravnborg , Peter Rosin The "fix" struct has a 2 byte hole after ->ywrapstep and the "fix = info->fix;" assignment doesn't necessarily clear it. It depends on the compiler. Fixes: 1f5e31d7e55a ("fbmem: don't call copy_from/to_user() with mutex held") Signed-off-by: Dan Carpenter --- I have 13 more similar places to patch... I'm not totally sure I understand all the issues involved. drivers/video/fbdev/core/fbmem.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index 6f6fc785b545..b4ce6a28aed9 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1109,6 +1109,7 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, ret = -EFAULT; break; case FBIOGET_FSCREENINFO: + memset(&fix, 0, sizeof(fix)); lock_fb_info(info); fix = info->fix; if (info->flags & FBINFO_HIDE_SMEM_START) -- 2.20.1 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Carpenter Subject: [PATCH] fbdev: potential information leak in do_fb_ioctl() Date: Tue, 29 Oct 2019 21:23:20 +0300 Message-ID: <20191029182320.GA17569@mwanda> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from userp2130.oracle.com (userp2130.oracle.com [156.151.31.86]) by gabe.freedesktop.org (Postfix) with ESMTPS id 50EE46E50B for ; 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Tue, 29 Oct 2019 18:23:30 GMT Received: from mwanda (/41.57.98.10) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 29 Oct 2019 11:23:30 -0700 Date: Tue, 29 Oct 2019 21:23:20 +0300 From: Dan Carpenter To: Bartlomiej Zolnierkiewicz , Andrea Righi Cc: Daniel Vetter , Sam Ravnborg , Maarten Lankhorst , Peter Rosin , Gerd Hoffmann , dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, security@kernel.org, Kees Cook , Julia Lawall Subject: [PATCH] fbdev: potential information leak in do_fb_ioctl() Message-ID: <20191029182320.GA17569@mwanda> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Mailer: git-send-email haha only kidding User-Agent: Mutt/1.10.1 (2018-07-13) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9425 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1910290160 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9425 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1910290160 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The "fix" struct has a 2 byte hole after ->ywrapstep and the "fix = info->fix;" assignment doesn't necessarily clear it. It depends on the compiler. Fixes: 1f5e31d7e55a ("fbmem: don't call copy_from/to_user() with mutex held") Signed-off-by: Dan Carpenter --- I have 13 more similar places to patch... I'm not totally sure I understand all the issues involved. drivers/video/fbdev/core/fbmem.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index 6f6fc785b545..b4ce6a28aed9 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1109,6 +1109,7 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, ret = -EFAULT; break; case FBIOGET_FSCREENINFO: + memset(&fix, 0, sizeof(fix)); lock_fb_info(info); fix = info->fix; if (info->flags & FBINFO_HIDE_SMEM_START) -- 2.20.1