linux-kernel - [patch] drm/vc4: Return -EFAULT on copy_from

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Date:	Tue, 8 Mar 2016 15:09:41 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	David Airlie <airlied@...ux.ie>, Eric Anholt <eric@...olt.net>
Cc:	"Luis R. Rodriguez" <mcgrof@...e.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Andrew Morton <akpm@...ux-foundation.org>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [patch] drm/vc4: Return -EFAULT on copy_from_user() failure

The copy_from_user() function returns the number of bytes not copied but
we want to return a negative error code.

Fixes: 463873d57014 ('drm/vc4: Add an API for creating GPU shaders in GEM BOs.')
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>

diff --git a/drivers/gpu/drm/vc4/vc4_bo.c b/drivers/gpu/drm/vc4/vc4_bo.c
index 034ef2d..9807bc9 100644
--- a/drivers/gpu/drm/vc4/vc4_bo.c
+++ b/drivers/gpu/drm/vc4/vc4_bo.c
@@ -498,11 +498,12 @@ vc4_create_shader_bo_ioctl(struct drm_device *dev, void *data,
 	if (IS_ERR(bo))
 		return PTR_ERR(bo);
 
-	ret = copy_from_user(bo->base.vaddr,
+	if (copy_from_user(bo->base.vaddr,
 			     (void __user *)(uintptr_t)args->data,
-			     args->size);
-	if (ret != 0)
+			     args->size)) {
+		ret = -EFAULT;
 		goto fail;
+	}
 	/* Clear the rest of the memory from allocating from the BO
 	 * cache.
 	 */