drm/i915: Fix lock order reversal with cliprects and cmdbuf in non-DRI2 paths.

This introduces allocation in the batch submission path that wasn't there
previously, but these are compatibility paths so we care about simplicity
more than performance.

kernel.org bug #12419.

Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Keith Packard <keithp@keithp.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 73 insertions, 34 deletions

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 6d21b9e48b89..ae83fe0ab374 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -356,7 +356,7 @@ static int validate_cmd(int cmd)
         return ret;
 }
 
-static int i915_emit_cmds(struct drm_device * dev, int __user * buffer, int dwords)
+static int i915_emit_cmds(struct drm_device * dev, int *buffer, int dwords)
 {
         drm_i915_private_t *dev_priv = dev->dev_private;
         int i;
@@ -370,8 +370,7 @@ static int i915_emit_cmds(struct drm_device * dev, int __user * buffer, int dwor
         for (i = 0; i < dwords;) {
                 int cmd, sz;
 
-                if (DRM_COPY_FROM_USER_UNCHECKED(&cmd, &buffer[i], sizeof(cmd)))
-                        return -EINVAL;
+                cmd = buffer[i];
 
                 if ((sz = validate_cmd(cmd)) == 0 || i + sz > dwords)
                         return -EINVAL;
@@ -379,11 +378,7 @@ static int i915_emit_cmds(struct drm_device * dev, int __user * buffer, int dwor
                 OUT_RING(cmd);
 
                 while (++i, --sz) {
-                        if (DRM_COPY_FROM_USER_UNCHECKED(&cmd, &buffer[i],
-                                                         sizeof(cmd))) {
-                                return -EINVAL;
-                        }
-                        OUT_RING(cmd);
+                        OUT_RING(buffer[i]);
                 }
         }
 
@@ -397,17 +392,13 @@ static int i915_emit_cmds(struct drm_device * dev, int __user * buffer, int dwor
 
 int
 i915_emit_box(struct drm_device *dev,
-              struct drm_clip_rect __user *boxes,
+              struct drm_clip_rect *boxes,
               int i, int DR1, int DR4)
 {
         drm_i915_private_t *dev_priv = dev->dev_private;
-        struct drm_clip_rect box;
+        struct drm_clip_rect box = boxes[i];
         RING_LOCALS;
 
-        if (DRM_COPY_FROM_USER_UNCHECKED(&box, &boxes[i], sizeof(box))) {
-                return -EFAULT;
-        }
-
         if (box.y2 <= box.y1 || box.x2 <= box.x1 || box.y2 <= 0 || box.x2 <= 0) {
                 DRM_ERROR("Bad box %d,%d..%d,%d\n",
                           box.x1, box.y1, box.x2, box.y2);
@@ -460,7 +451,9 @@ static void i915_emit_breadcrumb(struct drm_device *dev)
 }
 
 static int i915_dispatch_cmdbuffer(struct drm_device * dev,
-                                   drm_i915_cmdbuffer_t * cmd)
+                                   drm_i915_cmdbuffer_t *cmd,
+                                   struct drm_clip_rect *cliprects,
+                                   void *cmdbuf)
 {
         int nbox = cmd->num_cliprects;
         int i = 0, count, ret;
@@ -476,13 +469,13 @@ static int i915_dispatch_cmdbuffer(struct drm_device * dev,
 
         for (i = 0; i < count; i++) {
                 if (i < nbox) {
-                        ret = i915_emit_box(dev, cmd->cliprects, i,
+                        ret = i915_emit_box(dev, cliprects, i,
                                             cmd->DR1, cmd->DR4);
                         if (ret)
                                 return ret;
                 }
 
-                ret = i915_emit_cmds(dev, (int __user *)cmd->buf, cmd->sz / 4);
+                ret = i915_emit_cmds(dev, cmdbuf, cmd->sz / 4);
                 if (ret)
                         return ret;
         }
@@ -492,10 +485,10 @@ static int i915_dispatch_cmdbuffer(struct drm_device * dev,
 }
 
 static int i915_dispatch_batchbuffer(struct drm_device * dev,
-                                     drm_i915_batchbuffer_t * batch)
+                                     drm_i915_batchbuffer_t * batch,
+                                     struct drm_clip_rect *cliprects)
 {
         drm_i915_private_t *dev_priv = dev->dev_private;
-        struct drm_clip_rect __user *boxes = batch->cliprects;
         int nbox = batch->num_cliprects;
         int i = 0, count;
         RING_LOCALS;
@@ -511,7 +504,7 @@ static int i915_dispatch_batchbuffer(struct drm_device * dev,
 
         for (i = 0; i < count; i++) {
                 if (i < nbox) {
-                        int ret = i915_emit_box(dev, boxes, i,
+                        int ret = i915_emit_box(dev, cliprects, i,
                                                 batch->DR1, batch->DR4);
                         if (ret)
                                 return ret;
@@ -626,6 +619,7 @@ static int i915_batchbuffer(struct drm_device *dev, void *data,
             master_priv->sarea_priv;
         drm_i915_batchbuffer_t *batch = data;
         int ret;
+        struct drm_clip_rect *cliprects = NULL;
 
         if (!dev_priv->allow_batchbuffer) {
                 DRM_ERROR("Batchbuffer ioctl disabled\n");
@@ -637,17 +631,35 @@ static int i915_batchbuffer(struct drm_device *dev, void *data,
 
         RING_LOCK_TEST_WITH_RETURN(dev, file_priv);
 
-        if (batch->num_cliprects && DRM_VERIFYAREA_READ(batch->cliprects,
-                                                       batch->num_cliprects *
-                                                       sizeof(struct drm_clip_rect)))
-                return -EFAULT;
+        if (batch->num_cliprects < 0)
+                return -EINVAL;
+
+        if (batch->num_cliprects) {
+                cliprects = drm_calloc(batch->num_cliprects,
+                                       sizeof(struct drm_clip_rect),
+                                       DRM_MEM_DRIVER);
+                if (cliprects == NULL)
+                        return -ENOMEM;
+
+                ret = copy_from_user(cliprects, batch->cliprects,
+                                     batch->num_cliprects *
+                                     sizeof(struct drm_clip_rect));
+                if (ret != 0)
+                        goto fail_free;
+        }
 
         mutex_lock(&dev->struct_mutex);
-        ret = i915_dispatch_batchbuffer(dev, batch);
+        ret = i915_dispatch_batchbuffer(dev, batch, cliprects);
         mutex_unlock(&dev->struct_mutex);
 
         if (sarea_priv)
                 sarea_priv->last_dispatch = READ_BREADCRUMB(dev_priv);
+
+fail_free:
+        drm_free(cliprects,
+                 batch->num_cliprects * sizeof(struct drm_clip_rect),
+                 DRM_MEM_DRIVER);
+
         return ret;
 }
 
@@ -659,6 +671,8 @@ static int i915_cmdbuffer(struct drm_device *dev, void *data,
         drm_i915_sarea_t *sarea_priv = (drm_i915_sarea_t *)
             master_priv->sarea_priv;
         drm_i915_cmdbuffer_t *cmdbuf = data;
+        struct drm_clip_rect *cliprects = NULL;
+        void *batch_data;
         int ret;
 
         DRM_DEBUG("i915 cmdbuffer, buf %p sz %d cliprects %d\n",
@@ -666,25 +680,50 @@ static int i915_cmdbuffer(struct drm_device *dev, void *data,
 
         RING_LOCK_TEST_WITH_RETURN(dev, file_priv);
 
-        if (cmdbuf->num_cliprects &&
-            DRM_VERIFYAREA_READ(cmdbuf->cliprects,
-                                cmdbuf->num_cliprects *
-                                sizeof(struct drm_clip_rect))) {
-                DRM_ERROR("Fault accessing cliprects\n");
-                return -EFAULT;
+        if (cmdbuf->num_cliprects < 0)
+                return -EINVAL;
+
+        batch_data = drm_alloc(cmdbuf->sz, DRM_MEM_DRIVER);
+        if (batch_data == NULL)
+                return -ENOMEM;
+
+        ret = copy_from_user(batch_data, cmdbuf->buf, cmdbuf->sz);
+        if (ret != 0)
+                goto fail_batch_free;
+
+        if (cmdbuf->num_cliprects) {
+                cliprects = drm_calloc(cmdbuf->num_cliprects,
+                                       sizeof(struct drm_clip_rect),
+                                       DRM_MEM_DRIVER);
+                if (cliprects == NULL)
+                        goto fail_batch_free;
+
+                ret = copy_from_user(cliprects, cmdbuf->cliprects,
+                                     cmdbuf->num_cliprects *
+                                     sizeof(struct drm_clip_rect));
+                if (ret != 0)
+                        goto fail_clip_free;
         }
 
         mutex_lock(&dev->struct_mutex);
-        ret = i915_dispatch_cmdbuffer(dev, cmdbuf);
+        ret = i915_dispatch_cmdbuffer(dev, cmdbuf, cliprects, batch_data);
         mutex_unlock(&dev->struct_mutex);
         if (ret) {
                 DRM_ERROR("i915_dispatch_cmdbuffer failed\n");
-                return ret;
+                goto fail_batch_free;
         }
 
         if (sarea_priv)
                 sarea_priv->last_dispatch = READ_BREADCRUMB(dev_priv);
-        return 0;
+
+fail_batch_free:
+        drm_free(batch_data, cmdbuf->sz, DRM_MEM_DRIVER);
+fail_clip_free:
+        drm_free(cliprects,
+                 cmdbuf->num_cliprects * sizeof(struct drm_clip_rect),
+                 DRM_MEM_DRIVER);
+
+        return ret;
 }
 
 static int i915_flip_bufs(struct drm_device *dev, void *data,