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From:   Jens Wiklander <jens.wiklander@linaro.org>
To:     tee-dev@lists.linaro.org, linux-kernel@vger.kernel.org
Cc:     Jerome Forissier <jerome@forissier.org>,
        Sumit Garg <sumit.garg@linaro.org>,
        Etienne Carriere <etienne.carriere@linaro.org>,
        Rijo Thomas <Rijo-john.Thomas@amd.com>,
        Devaraj Rangasamy <Devaraj.Rangasamy@amd.com>,
        Jens Wiklander <jens.wiklander@linaro.org>
Subject: [PATCH 3/5] tee: don't assign shm id for private shms
Date:   Thu,  9 Jan 2020 13:36:49 +0100
Message-Id: <20200109123651.18520-4-jens.wiklander@linaro.org>
In-Reply-To: <20200109123651.18520-1-jens.wiklander@linaro.org>
References: <20200109123651.18520-1-jens.wiklander@linaro.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Private shared memory object must not be referenced from user space. To
guarantee that, don't assign an id to shared memory objects which are
driver private.

Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
---
 drivers/tee/tee_private.h |  3 ++-
 drivers/tee/tee_shm.c     | 31 ++++++++++++++++++-------------
 2 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/drivers/tee/tee_private.h b/drivers/tee/tee_private.h
index f797171f0434..e55204df31ce 100644
--- a/drivers/tee/tee_private.h
+++ b/drivers/tee/tee_private.h
@@ -37,7 +37,8 @@ struct tee_shm_pool {
  * @num_users:	number of active users of this device
  * @c_no_user:	completion used when unregistering the device
  * @mutex:	mutex protecting @num_users and @idr
- * @idr:	register of shared memory object allocated on this device
+ * @idr:	register of user space shared memory objects allocated or
+ *		registered on this device
  * @pool:	shared memory pool
  */
 struct tee_device {
diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
index 8afe08b23242..e636cf82acdb 100644
--- a/drivers/tee/tee_shm.c
+++ b/drivers/tee/tee_shm.c
@@ -15,9 +15,11 @@ static void tee_shm_release(struct tee_shm *shm)
 {
 	struct tee_device *teedev = shm->teedev;
 
-	mutex_lock(&teedev->mutex);
-	idr_remove(&teedev->idr, shm->id);
-	mutex_unlock(&teedev->mutex);
+	if (shm->flags & TEE_SHM_DMA_BUF) {
+		mutex_lock(&teedev->mutex);
+		idr_remove(&teedev->idr, shm->id);
+		mutex_unlock(&teedev->mutex);
+	}
 
 	if (shm->flags & TEE_SHM_POOL) {
 		struct tee_shm_pool_mgr *poolm;
@@ -143,17 +145,18 @@ struct tee_shm *tee_shm_alloc(struct tee_context *ctx, size_t size, u32 flags)
 		goto err_kfree;
 	}
 
-	mutex_lock(&teedev->mutex);
-	shm->id = idr_alloc(&teedev->idr, shm, 1, 0, GFP_KERNEL);
-	mutex_unlock(&teedev->mutex);
-	if (shm->id < 0) {
-		ret = ERR_PTR(shm->id);
-		goto err_pool_free;
-	}
 
 	if (flags & TEE_SHM_DMA_BUF) {
 		DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 
+		mutex_lock(&teedev->mutex);
+		shm->id = idr_alloc(&teedev->idr, shm, 1, 0, GFP_KERNEL);
+		mutex_unlock(&teedev->mutex);
+		if (shm->id < 0) {
+			ret = ERR_PTR(shm->id);
+			goto err_pool_free;
+		}
+
 		exp_info.ops = &tee_shm_dma_buf_ops;
 		exp_info.size = shm->size;
 		exp_info.flags = O_RDWR;
@@ -171,9 +174,11 @@ struct tee_shm *tee_shm_alloc(struct tee_context *ctx, size_t size, u32 flags)
 
 	return shm;
 err_rem:
-	mutex_lock(&teedev->mutex);
-	idr_remove(&teedev->idr, shm->id);
-	mutex_unlock(&teedev->mutex);
+	if (flags & TEE_SHM_DMA_BUF) {
+		mutex_lock(&teedev->mutex);
+		idr_remove(&teedev->idr, shm->id);
+		mutex_unlock(&teedev->mutex);
+	}
 err_pool_free:
 	poolm->ops->free(poolm, shm);
 err_kfree:
-- 
2.17.1