linux-kernel - [PATCH] drm/vc4: Fix OOPSes from trying to cache a partially constructed BO.

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Message-Id: <20170209181600.24048-1-eric@anholt.net>
Date:   Thu,  9 Feb 2017 10:16:00 -0800
From:   Eric Anholt <eric@...olt.net>
To:     dri-devel@...ts.freedesktop.org
Cc:     linux-kernel@...r.kernel.org, pbrobinson@...il.com,
        Eric Anholt <eric@...olt.net>
Subject: [PATCH] drm/vc4: Fix OOPSes from trying to cache a partially constructed BO.

If a CMA allocation failed, the partially constructed BO would be
unreferenced through the normal path, and we might choose to put it in
the BO cache.  If we then reused it before it expired from the cache,
the kernel would OOPS.

Signed-off-by: Eric Anholt <eric@...olt.net>
Fixes: c826a6e10644 ("drm/vc4: Add a BO cache.")
---
 drivers/gpu/drm/vc4/vc4_bo.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/vc4/vc4_bo.c b/drivers/gpu/drm/vc4/vc4_bo.c
index 5ec14f25625d..fd83a2807656 100644
--- a/drivers/gpu/drm/vc4/vc4_bo.c
+++ b/drivers/gpu/drm/vc4/vc4_bo.c
@@ -314,6 +314,14 @@ void vc4_free_object(struct drm_gem_object *gem_bo)
 		goto out;
 	}
 
+	/* If this object was partially constructed but CMA allocation
+	 * had failed, just free it.
+	 */
+	if (!bo->base.vaddr) {
+		vc4_bo_destroy(bo);
+		goto out;
+	}
+
 	cache_list = vc4_get_cache_list_for_size(dev, gem_bo->size);
 	if (!cache_list) {
 		vc4_bo_destroy(bo);
-- 
2.11.0