linux-kernel - [PATCH 02/38] media: v4l2-ioctl: avoid memory leaks on some time32 compat functions

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Date:   Wed,  2 Sep 2020 18:10:05 +0200
From:   Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Arnd Bergmann <arnd@...db.de>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Vandana BN <bnvandana@...il.com>,
        Niklas Söderlund 
        <niklas.soderlund+renesas@...natech.se>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 02/38] media: v4l2-ioctl: avoid memory leaks on some time32 compat functions

There are some reports about possible memory leaks:

	drivers/media/v4l2-core//v4l2-ioctl.c:3203 video_put_user() warn: check that 'ev32' doesn't leak information (struct has a hole after 'type')
	drivers/media/v4l2-core//v4l2-ioctl.c:3230 video_put_user() warn: check that 'vb32' doesn't leak information (struct has a hole after 'memory')

While smatch seems to be reporting a false positive (line 3203),
there's indeed a possible leak with reserved2 at vb32.

We might have fixed just that one, but smatch checks won't
be able to check leaks at ev32. So, re-work the code in a way
that will ensure that the var contents will be zeroed before
filling it.

With that, we don't need anymore to touch reserved fields.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
---
 drivers/media/v4l2-core/v4l2-ioctl.c | 48 ++++++++++++++--------------
 1 file changed, 24 insertions(+), 24 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index a556880f225a..6f3fe9c4b64a 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -3189,17 +3189,16 @@ static int video_put_user(void __user *arg, void *parg, unsigned int cmd)
 #ifdef CONFIG_COMPAT_32BIT_TIME
 	case VIDIOC_DQEVENT_TIME32: {
 		struct v4l2_event *ev = parg;
-		struct v4l2_event_time32 ev32 = {
-			.type		= ev->type,
-			.pending	= ev->pending,
-			.sequence	= ev->sequence,
-			.timestamp.tv_sec  = ev->timestamp.tv_sec,
-			.timestamp.tv_nsec = ev->timestamp.tv_nsec,
-			.id		= ev->id,
-		};
+		struct v4l2_event_time32 ev32;
 
+		memset(&ev32, 0, sizeof(ev32));
+		ev32.type		= ev->type,
+		ev32.pending		= ev->pending,
+		ev32.sequence		= ev->sequence,
+		ev32.timestamp.tv_sec	= ev->timestamp.tv_sec,
+		ev32.timestamp.tv_nsec	= ev->timestamp.tv_nsec,
+		ev32.id			= ev->id,
 		memcpy(&ev32.u, &ev->u, sizeof(ev->u));
-		memcpy(&ev32.reserved, &ev->reserved, sizeof(ev->reserved));
 
 		if (copy_to_user(arg, &ev32, sizeof(ev32)))
 			return -EFAULT;
@@ -3210,21 +3209,22 @@ static int video_put_user(void __user *arg, void *parg, unsigned int cmd)
 	case VIDIOC_DQBUF_TIME32:
 	case VIDIOC_PREPARE_BUF_TIME32: {
 		struct v4l2_buffer *vb = parg;
-		struct v4l2_buffer_time32 vb32 = {
-			.index		= vb->index,
-			.type		= vb->type,
-			.bytesused	= vb->bytesused,
-			.flags		= vb->flags,
-			.field		= vb->field,
-			.timestamp.tv_sec	= vb->timestamp.tv_sec,
-			.timestamp.tv_usec	= vb->timestamp.tv_usec,
-			.timecode	= vb->timecode,
-			.sequence	= vb->sequence,
-			.memory		= vb->memory,
-			.m.userptr	= vb->m.userptr,
-			.length		= vb->length,
-			.request_fd	= vb->request_fd,
-		};
+		struct v4l2_buffer_time32 vb32;
+
+		memset(&vb32, 0, sizeof(vb32));
+		vb32.index		= vb->index,
+		vb32.type		= vb->type,
+		vb32.bytesused		= vb->bytesused,
+		vb32.flags		= vb->flags,
+		vb32.field		= vb->field,
+		vb32.timestamp.tv_sec	= vb->timestamp.tv_sec,
+		vb32.timestamp.tv_usec	= vb->timestamp.tv_usec,
+		vb32.timecode		= vb->timecode,
+		vb32.sequence		= vb->sequence,
+		vb32.memory		= vb->memory,
+		vb32.length		= vb->length,
+		vb32.request_fd		= vb->request_fd,
+		memcpy(&vb32.m, &vb->m, sizeof(vb->m));
 
 		if (copy_to_user(arg, &vb32, sizeof(vb32)))
 			return -EFAULT;
-- 
2.26.2