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drm/msm: fix potential NULL dereference in cleanup

PATCH New Dan Carpenter 1 participant 2 messages Oct 13, 2021

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DRM drivers Arm Qualcomm mailing list Kernel janitors DRM driver for Qualcomm display hardware
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Dan Carpenter

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#0 lore raw

PATCH 1/2 drm/msm: fix potential NULL dereference in cleanup

The "msm_obj->node" list needs to be initialized earlier so that the list_del() in msm_gem_free_object() doesn't experience a NULL pointer dereference.

Fixes 6ed0897cd800 ("drm/msm: Fix debugfs deadlock")
Signed-off-by Dan Carpenter <[email protected]>
---
 drivers/gpu/drm/msm/msm_gem.c | 1 +
 1 file changed, 1 insertion(+)
drivers/gpu/drm/msm/msm_gem.c +1 -0
index 40a9863f5951..49185d524be3 100644
@@ -1132,6 +1132,7 @@ static int msm_gem_new_impl(struct drm_device *dev,
 	msm_obj->flags = flags;
 	msm_obj->madv = MSM_MADV_WILLNEED;
 
+	INIT_LIST_HEAD(&msm_obj->node);
 	INIT_LIST_HEAD(&msm_obj->vmas);
 
 	*obj = &msm_obj->base;
Signature · 1 line
2.20.1
author
#1 lore raw

PATCH 2/2 drm/msm: uninitialized variable in msm_gem_import()

The msm_gem_new_impl() function cleans up after itself so there is no need to call drm_gem_object_put(). Conceptually, it does not make sense to call a kref_put() function until after the reference counting has been initialized which happens immediately after this call in the drm_gem_(private_)object_init() functions.

In the msm_gem_import() function the "obj" pointer is uninitialized, so it will lead to a crash.

Fixes 05b849111c07 ("drm/msm: prime support")
Signed-off-by Dan Carpenter <[email protected]>
---
 drivers/gpu/drm/msm/msm_gem.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
drivers/gpu/drm/msm/msm_gem.c +2 -2
index 49185d524be3..0e491cd21c53 100644
@@ -1167,7 +1167,7 @@ struct drm_gem_object *msm_gem_new(struct drm_device *dev, uint32_t size, uint32
 
 	ret = msm_gem_new_impl(dev, size, flags, &obj);
 	if (ret)
-		goto fail;
+		return ERR_PTR(ret);
 
 	msm_obj = to_msm_bo(obj);
 

@@ -1251,7 +1251,7 @@ struct drm_gem_object *msm_gem_import(struct drm_device *dev,
 
 	ret = msm_gem_new_impl(dev, size, MSM_BO_WC, &obj);
 	if (ret)
-		goto fail;
+		return ERR_PTR(ret);
 
 	drm_gem_private_object_init(dev, obj, size);
Signature · 1 line
2.20.1