linux-kernel - [PATCH] drm/vc4: Fix resource leak in 'vc4_get_hang_state

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Date:   Wed, 10 May 2017 05:53:56 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     eric@...olt.net, airlied@...ux.ie
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>
Subject: [PATCH] drm/vc4: Fix resource leak in 'vc4_get_hang_state_ioctl()' in error handling path

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 in the error
    handling path. This has the side effect to also try to free it if the
    first 'kcalloc' fails. This is harmless.
  - delete already allocated handles
  - 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@...adoo.fr>
---
This patch also add the 'vc4_free_hang_state()' call in the error
handling path. It sounds logical to me, but I'm not sure of it.
---
 drivers/gpu/drm/vc4/vc4_gem.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_gem.c b/drivers/gpu/drm/vc4/vc4_gem.c
index e9c381c42139..891c7a22cf81 100644
--- a/drivers/gpu/drm/vc4/vc4_gem.c
+++ b/drivers/gpu/drm/vc4/vc4_gem.c
@@ -111,8 +111,8 @@ 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_free;
 		}
 		bo_state[i].handle = handle;
 		bo_state[i].paddr = vc4_bo->base.paddr;
@@ -124,13 +124,16 @@ vc4_get_hang_state_ioctl(struct drm_device *dev, void *data,
 			 state->bo_count * sizeof(*bo_state)))
 		ret = -EFAULT;
 
-	kfree(bo_state);
-
 err_free:
-
 	vc4_free_hang_state(dev, kernel_state);
 
-err:
+	if (ret) {
+		for (i = 0; i < state->bo_count; i++)
+			drm_gem_handle_delete(file_priv, bo_state[i].handle);
+	}
+
+	kfree(bo_state);
+
 	return ret;
 }
 
-- 
2.11.0