[PATCH AUTOSEL for 4.9 261/281] drm/vc4: Fix resource leak in 'vc4_get_hang_state_ioctl()' in error handling path

[Sasha Levin]

From: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>

[ Upstream commit d0b1d259a4b58b21a21ea82d7174bf7ea825e9cc ]

If one 'drm_gem_handle_create()' fails, we leak somes handles and some
memory.

In order to fix it:
  - move the 'free(bo_state)' at the end of the function so that it is also
    called in the eror handling path. This has the side effect to also try
    to free it if the first 'kcalloc' fails. This is harmless.
  - add a new label, err_delete_handle, in order to delete already
    allocated handles in error handling path
  - remove the now useless 'err' label

The way the code is now written will also delete the handles if the
'copy_to_user()' call fails.

Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
Reviewed-by: Eric Anholt <eric@xxxxxxxxxx>
Link: http://patchwork.freedesktop.org/patch/msgid/20170512123803.1886-1-christophe.jaillet@xxxxxxxxxx
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 drivers/gpu/drm/vc4/vc4_gem.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_gem.c b/drivers/gpu/drm/vc4/vc4_gem.c
index ab3016982466..b608cd463d4e 100644
--- a/drivers/gpu/drm/vc4/vc4_gem.c
+++ b/drivers/gpu/drm/vc4/vc4_gem.c
@@ -110,8 +110,8 @@ vc4_get_hang_state_ioctl(struct drm_device *dev, void *data,
 					    &handle);
 
 		if (ret) {
-			state->bo_count = i - 1;
-			goto err;
+			state->bo_count = i;
+			goto err_delete_handle;
 		}
 		bo_state[i].handle = handle;
 		bo_state[i].paddr = vc4_bo->base.paddr;
@@ -123,13 +123,16 @@ vc4_get_hang_state_ioctl(struct drm_device *dev, void *data,
 			 state->bo_count * sizeof(*bo_state)))
 		ret = -EFAULT;
 
-	kfree(bo_state);
+err_delete_handle:
+	if (ret) {
+		for (i = 0; i < state->bo_count; i++)
+			drm_gem_handle_delete(file_priv, bo_state[i].handle);
+	}
 
 err_free:
-
 	vc4_free_hang_state(dev, kernel_state);
+	kfree(bo_state);
 
-err:
 	return ret;
 }
 
-- 
2.14.1