[PATCH v4 02/17] drm/vmwgfx: Fix frame-size warning in vmw_mksstat_add_ioctl

[Zack Rusin]

From: Martin Krastev <krastevm at vmware.com>

Function vmw_mksstat_add_ioctl allocates three big arrays on stack.
That triggers frame-size [-Wframe-larger-than=] warning. Refactor
that function to use kmalloc_array instead.

v2: Initialize page to null to avoid possible uninitialized use of it,
    spotted by the kernel test robot <lkp at intel.com>

Signed-off-by: Martin Krastev <krastevm at vmware.com>
Reviewed-by: Zack Rusin <zackr at vmware.com>
Reviewed-by: Maaz Mombasawala <mombasawalam at vmware.com>
Signed-off-by: Zack Rusin <zackr at vmware.com>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_msg.c | 43 +++++++++++++++++++----------
 1 file changed, 29 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c b/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c
index 089046fa21be..50d8b9bcd72a 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c
@@ -1014,8 +1014,6 @@ int vmw_mksstat_add_ioctl(struct drm_device *dev, void *data,
 
 	struct vmw_private *const dev_priv = vmw_priv(dev);
 
-	struct page *page;
-	MKSGuestStatInstanceDescriptor *pdesc;
 	const size_t num_pages_stat = PFN_UP(arg->stat_len);
 	const size_t num_pages_info = PFN_UP(arg->info_len);
 	const size_t num_pages_strs = PFN_UP(arg->strs_len);
@@ -1023,10 +1021,13 @@ int vmw_mksstat_add_ioctl(struct drm_device *dev, void *data,
 	long nr_pinned_stat;
 	long nr_pinned_info;
 	long nr_pinned_strs;
-	struct page *pages_stat[ARRAY_SIZE(pdesc->statPPNs)];
-	struct page *pages_info[ARRAY_SIZE(pdesc->infoPPNs)];
-	struct page *pages_strs[ARRAY_SIZE(pdesc->strsPPNs)];
+	MKSGuestStatInstanceDescriptor *pdesc;
+	struct page *page = NULL;
+	struct page **pages_stat = NULL;
+	struct page **pages_info = NULL;
+	struct page **pages_strs = NULL;
 	size_t i, slot;
+	int ret_err = -ENOMEM;
 
 	arg->id = -1;
 
@@ -1054,13 +1055,23 @@ int vmw_mksstat_add_ioctl(struct drm_device *dev, void *data,
 
 	BUG_ON(dev_priv->mksstat_user_pages[slot]);
 
+	/* Allocate statically-sized temp arrays for pages -- too big to keep in frame */
+	pages_stat = (struct page **)kmalloc_array(
+		ARRAY_SIZE(pdesc->statPPNs) +
+		ARRAY_SIZE(pdesc->infoPPNs) +
+		ARRAY_SIZE(pdesc->strsPPNs), sizeof(*pages_stat), GFP_KERNEL);
+
+	if (!pages_stat)
+		goto err_nomem;
+
+	pages_info = pages_stat + ARRAY_SIZE(pdesc->statPPNs);
+	pages_strs = pages_info + ARRAY_SIZE(pdesc->infoPPNs);
+
 	/* Allocate a page for the instance descriptor */
 	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
 
-	if (!page) {
-		atomic_set(&dev_priv->mksstat_user_pids[slot], 0);
-		return -ENOMEM;
-	}
+	if (!page)
+		goto err_nomem;
 
 	/* Set up the instance descriptor */
 	pdesc = page_address(page);
@@ -1075,9 +1086,8 @@ int vmw_mksstat_add_ioctl(struct drm_device *dev, void *data,
 		ARRAY_SIZE(pdesc->description) - 1);
 
 	if (desc_len < 0) {
-		atomic_set(&dev_priv->mksstat_user_pids[slot], 0);
-		__free_page(page);
-		return -EFAULT;
+		ret_err = -EFAULT;
+		goto err_nomem;
 	}
 
 	reset_ppn_array(pdesc->statPPNs, ARRAY_SIZE(pdesc->statPPNs));
@@ -1118,6 +1128,7 @@ int vmw_mksstat_add_ioctl(struct drm_device *dev, void *data,
 
 	DRM_DEV_INFO(dev->dev, "pid=%d arg.description='%.*s' id=%zu\n", current->pid, (int)desc_len, pdesc->description, slot);
 
+	kfree(pages_stat);
 	return 0;
 
 err_pin_strs:
@@ -1132,9 +1143,13 @@ int vmw_mksstat_add_ioctl(struct drm_device *dev, void *data,
 	if (nr_pinned_stat > 0)
 		unpin_user_pages(pages_stat, nr_pinned_stat);
 
+err_nomem:
 	atomic_set(&dev_priv->mksstat_user_pids[slot], 0);
-	__free_page(page);
-	return -ENOMEM;
+	if (page)
+		__free_page(page);
+	kfree(pages_stat);
+
+	return ret_err;
 }
 
 /**
-- 
2.34.1