From: Al Viro <viro@zeniv.linux.org.uk>
Date: Wed, 24 May 2017 17:54:09 -0400
Subject: switch compat_drm_infobufs() to drm_ioctl_kernel()
Git-commit: 5c7640ab625829fd08b7fa0160c6fd188e70b5fe
Patch-mainline: v4.13-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/drm_bufs.c   |   48 +++++++++++++++++++----------------
 drivers/gpu/drm/drm_ioc32.c  |   58 +++++++++++++++++--------------------------
 drivers/gpu/drm/drm_legacy.h |    3 ++
 3 files changed, 53 insertions(+), 56 deletions(-)

--- a/drivers/gpu/drm/drm_bufs.c
+++ b/drivers/gpu/drm/drm_bufs.c
@@ -1258,11 +1258,11 @@ int drm_legacy_addbufs(struct drm_device
  * lock, preventing of allocating more buffers after this call. Information
  * about each requested buffer is then copied into user space.
  */
-int drm_legacy_infobufs(struct drm_device *dev, void *data,
-			struct drm_file *file_priv)
+int __drm_legacy_infobufs(struct drm_device *dev,
+			void *data, int *p,
+			int (*f)(void *, int, struct drm_buf_entry *))
 {
 	struct drm_device_dma *dma = dev->dma;
-	struct drm_buf_info *request = data;
 	int i;
 	int count;
 
@@ -1290,26 +1290,12 @@ int drm_legacy_infobufs(struct drm_devic
 
 	DRM_DEBUG("count = %d\n", count);
 
-	if (request->count >= count) {
+	if (*p >= count) {
 		for (i = 0, count = 0; i < DRM_MAX_ORDER + 1; i++) {
-			if (dma->bufs[i].buf_count) {
-				struct drm_buf_desc __user *to =
-				    &request->list[count];
-				struct drm_buf_entry *from = &dma->bufs[i];
-				if (copy_to_user(&to->count,
-						 &from->buf_count,
-						 sizeof(from->buf_count)) ||
-				    copy_to_user(&to->size,
-						 &from->buf_size,
-						 sizeof(from->buf_size)) ||
-				    copy_to_user(&to->low_mark,
-						 &from->low_mark,
-						 sizeof(from->low_mark)) ||
-				    copy_to_user(&to->high_mark,
-						 &from->high_mark,
-						 sizeof(from->high_mark)))
+			struct drm_buf_entry *from = &dma->bufs[i];
+			if (from->buf_count) {
+				if (f(data, count, from) < 0)
 					return -EFAULT;
-
 				DRM_DEBUG("%d %d %d %d %d\n",
 					  i,
 					  dma->bufs[i].buf_count,
@@ -1320,11 +1306,29 @@ int drm_legacy_infobufs(struct drm_devic
 			}
 		}
 	}
-	request->count = count;
+	*p = count;
 
 	return 0;
 }
 
+static int copy_one_buf(void *data, int count, struct drm_buf_entry *from)
+{
+	struct drm_buf_info *request = data;
+	struct drm_buf_desc __user *to = &request->list[count];
+	struct drm_buf_desc v = {.count = from->buf_count,
+				 .size = from->buf_size,
+				 .low_mark = from->low_mark,
+				 .high_mark = from->high_mark};
+	return copy_to_user(to, &v, offsetof(struct drm_buf_desc, flags));
+}
+
+int drm_legacy_infobufs(struct drm_device *dev, void *data,
+			struct drm_file *file_priv)
+{
+	struct drm_buf_info *request = data;
+	return __drm_legacy_infobufs(dev, data, &request->count, copy_one_buf);
+}
+
 /**
  * Specifies a low and high water mark for buffer allocation
  *
--- a/drivers/gpu/drm/drm_ioc32.c
+++ b/drivers/gpu/drm/drm_ioc32.c
@@ -396,52 +396,42 @@ typedef struct drm_buf_info32 {
 	u32 list;
 } drm_buf_info32_t;
 
+static int copy_one_buf32(void *data, int count, struct drm_buf_entry *from)
+{
+	drm_buf_info32_t *request = data;
+	drm_buf_desc32_t __user *to = compat_ptr(request->list);
+	drm_buf_desc32_t v = {.count = from->buf_count,
+			      .size = from->buf_size,
+			      .low_mark = from->low_mark,
+			      .high_mark = from->high_mark};
+	return copy_to_user(to + count, &v, offsetof(drm_buf_desc32_t, flags));
+}
+
+static int drm_legacy_infobufs32(struct drm_device *dev, void *data,
+			struct drm_file *file_priv)
+{
+	drm_buf_info32_t *request = data;
+	return __drm_legacy_infobufs(dev, data, &request->count, copy_one_buf32);
+}
+
 static int compat_drm_infobufs(struct file *file, unsigned int cmd,
 			       unsigned long arg)
 {
 	drm_buf_info32_t req32;
 	drm_buf_info32_t __user *argp = (void __user *)arg;
-	drm_buf_desc32_t __user *to;
-	struct drm_buf_info __user *request;
-	struct drm_buf_desc __user *list;
-	size_t nbytes;
-	int i, err;
-	int count, actual;
+	int err;
 
 	if (copy_from_user(&req32, argp, sizeof(req32)))
 		return -EFAULT;
 
-	count = req32.count;
-	to = (drm_buf_desc32_t __user *) (unsigned long)req32.list;
-	if (count < 0)
-		count = 0;
-	if (count > 0
-	    && !access_ok(VERIFY_WRITE, to, count * sizeof(drm_buf_desc32_t)))
-		return -EFAULT;
+	if (req32.count < 0)
+		req32.count = 0;
 
-	nbytes = sizeof(*request) + count * sizeof(struct drm_buf_desc);
-	request = compat_alloc_user_space(nbytes);
-	if (!request)
-		return -EFAULT;
-	list = (struct drm_buf_desc *) (request + 1);
-
-	if (__put_user(count, &request->count)
-	    || __put_user(list, &request->list))
-		return -EFAULT;
-
-	err = drm_ioctl(file, DRM_IOCTL_INFO_BUFS, (unsigned long)request);
+	err = drm_ioctl_kernel(file, drm_legacy_infobufs32, &req32, DRM_AUTH);
 	if (err)
 		return err;
 
-	if (__get_user(actual, &request->count))
-		return -EFAULT;
-	if (count >= actual)
-		for (i = 0; i < actual; ++i)
-			if (__copy_in_user(&to[i], &list[i],
-					   offsetof(struct drm_buf_desc, flags)))
-				return -EFAULT;
-
-	if (__put_user(actual, &argp->count))
+	if (put_user(req32.count, &argp->count))
 		return -EFAULT;
 
 	return 0;
@@ -1053,7 +1043,7 @@ static struct {
 	[DRM_IOCTL_NR(DRM_IOCTL_ADD_MAP32)].fn = compat_drm_addmap,
 	DRM_IOCTL32_DEF(DRM_IOCTL_ADD_BUFS, compat_drm_addbufs),
 	[DRM_IOCTL_NR(DRM_IOCTL_MARK_BUFS32)].fn = compat_drm_markbufs,
-	[DRM_IOCTL_NR(DRM_IOCTL_INFO_BUFS32)].fn = compat_drm_infobufs,
+	DRM_IOCTL32_DEF(DRM_IOCTL_INFO_BUFS, compat_drm_infobufs),
 	[DRM_IOCTL_NR(DRM_IOCTL_MAP_BUFS32)].fn = compat_drm_mapbufs,
 	[DRM_IOCTL_NR(DRM_IOCTL_FREE_BUFS32)].fn = compat_drm_freebufs,
 	[DRM_IOCTL_NR(DRM_IOCTL_RM_MAP32)].fn = compat_drm_rmmap,
--- a/drivers/gpu/drm/drm_legacy.h
+++ b/drivers/gpu/drm/drm_legacy.h
@@ -74,6 +74,9 @@ int drm_legacy_freebufs(struct drm_devic
 int drm_legacy_mapbufs(struct drm_device *d, void *v, struct drm_file *f);
 int drm_legacy_dma_ioctl(struct drm_device *d, void *v, struct drm_file *f);
 
+int __drm_legacy_infobufs(struct drm_device *, void *, int *,
+			  int (*)(void *, int, struct drm_buf_entry *));
+
 #ifdef CONFIG_DRM_VM
 void drm_legacy_vma_flush(struct drm_device *d);
 #else