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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: "Sasha Levin" <sashal@kernel.org>,
	"Xin Tan" <tanxin.ctf@gmail.com>,
	"Xiyu Yang" <xiyuyang19@fudan.edu.cn>,
	dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
	"Christian König" <christian.koenig@amd.com>,
	linux-media@vger.kernel.org
Subject: [PATCH AUTOSEL 5.7 06/53] drm/ttm: Fix dma_fence refcnt leak in ttm_bo_vm_fault_reserved
Date: Wed,  1 Jul 2020 21:21:15 -0400	[thread overview]
Message-ID: <20200702012202.2700645-6-sashal@kernel.org> (raw)
In-Reply-To: <20200702012202.2700645-1-sashal@kernel.org>

From: Xiyu Yang <xiyuyang19@fudan.edu.cn>

[ Upstream commit 37cc4b95d13f311c04aa8e9daacca3905ad45ca7 ]

ttm_bo_vm_fault_reserved() invokes dma_fence_get(), which returns a
reference of the specified dma_fence object to "moving" with increased
refcnt.

When ttm_bo_vm_fault_reserved() returns, local variable "moving" becomes
invalid, so the refcount should be decreased to keep refcount balanced.

The reference counting issue happens in several exception handling paths
of ttm_bo_vm_fault_reserved(). When those error scenarios occur such as
"err" equals to -EBUSY, the function forgets to decrease the refcnt
increased by dma_fence_get(), causing a refcnt leak.

Fix this issue by calling dma_fence_put() when no_wait_gpu flag is
equals to true.

Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/370219/
Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/ttm/ttm_bo_vm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 0ad30b1129821..72100b84c7a90 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -300,8 +300,10 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
 			break;
 		case -EBUSY:
 		case -ERESTARTSYS:
+			dma_fence_put(moving);
 			return VM_FAULT_NOPAGE;
 		default:
+			dma_fence_put(moving);
 			return VM_FAULT_SIGBUS;
 		}
 
-- 
2.25.1

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       reply	other threads:[~2020-07-02  1:23 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200702012202.2700645-1-sashal@kernel.org>
2020-07-02  1:21 ` Sasha Levin [this message]
2020-07-02  1:21 ` [PATCH AUTOSEL 5.7 07/53] drm/ttm: Fix dma_fence refcnt leak when adding move fence Sasha Levin
2020-07-02  1:21 ` [PATCH AUTOSEL 5.7 08/53] gpu: host1x: Clean up debugfs in error handling path Sasha Levin
2020-07-02  1:21 ` [PATCH AUTOSEL 5.7 09/53] drm/tegra: hub: Do not enable orphaned window group Sasha Levin
2020-07-02  1:21 ` [PATCH AUTOSEL 5.7 10/53] gpu: host1x: Detach driver on unregister Sasha Levin
2020-07-02  1:21 ` [PATCH AUTOSEL 5.7 13/53] drm: mcde: Fix display initialization problem Sasha Levin
2020-07-02  1:21 ` [PATCH AUTOSEL 5.7 33/53] drm: panel-orientation-quirks: Add quirk for Asus T101HA panel Sasha Levin
2020-07-02  1:21 ` [PATCH AUTOSEL 5.7 34/53] drm: panel-orientation-quirks: Use generic orientation-data for Acer S1003 Sasha Levin
2020-07-02  1:21 ` [PATCH AUTOSEL 5.7 38/53] drm/sun4i: mixer: Call of_dma_configure if there's an IOMMU Sasha Levin

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