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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>,
        Xin Xiong <xiongx18@fudan.edu.cn>,
        Xin Tan <tanxin.ctf@gmail.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 011/171] drm/amd/amdgpu/amdgpu_cs: fix refcount leak of a dma_fence obj
Date:   Tue, 12 Apr 2022 08:28:22 +0200
Message-Id: <20220412062928.209847133@linuxfoundation.org>
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From: Xin Xiong <xiongx18@fudan.edu.cn>

[ Upstream commit dfced44f122c500004a48ecc8db516bb6a295a1b ]

This issue takes place in an error path in
amdgpu_cs_fence_to_handle_ioctl(). When `info->in.what` falls into
default case, the function simply returns -EINVAL, forgetting to
decrement the reference count of a dma_fence obj, which is bumped
earlier by amdgpu_cs_get_fence(). This may result in reference count
leaks.

Fix it by decreasing the refcount of specific object before returning
the error code.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Xin Xiong <xiongx18@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
index 12598a4b5c78..867fcee6b0d3 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
@@ -1484,6 +1484,7 @@ int amdgpu_cs_fence_to_handle_ioctl(struct drm_device *dev, void *data,
 		return 0;
 
 	default:
+		dma_fence_put(fence);
 		return -EINVAL;
 	}
 }
-- 
2.35.1