linux-kernel - Re: [PATCH V1] accel/amdxdna: Fix potential NULL pointer dereference in context cleanup

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Message-ID: <36165050-73c0-4ed8-85d3-42a874ae125f@amd.com>
Date: Thu, 11 Dec 2025 15:50:42 -0600
From: Mario Limonciello <mario.limonciello@....com>
To: Lizhi Hou <lizhi.hou@....com>, ogabbay@...nel.org,
 quic_jhugo@...cinc.com, dri-devel@...ts.freedesktop.org,
 maciej.falkowski@...ux.intel.com
Cc: linux-kernel@...r.kernel.org, max.zhen@....com, sonal.santan@....com
Subject: Re: [PATCH V1] accel/amdxdna: Fix potential NULL pointer dereference
 in context cleanup

On 12/10/25 10:56 PM, Lizhi Hou wrote:
> aie_destroy_context() is invoked during error handling in
> aie2_create_context(). However, aie_destroy_context() assumes that the
> context's mailbox channel pointer is non-NULL. If mailbox channel
> creation fails, the pointer remains NULL and calling aie_destroy_context()
> can lead to a NULL pointer dereference.
> 
> In aie2_create_context(), replace aie_destroy_context() with a function
> which request firmware to remove the context created previously.
> 
> Fixes: be462c97b7df ("accel/amdxdna: Add hardware context")
> Signed-off-by: Lizhi Hou <lizhi.hou@....com>
> ---
>   drivers/accel/amdxdna/aie2_message.c | 52 +++++++++++++++-------------
>   1 file changed, 28 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/accel/amdxdna/aie2_message.c b/drivers/accel/amdxdna/aie2_message.c
> index 03b75757a6e6..980aef9dc51a 100644
> --- a/drivers/accel/amdxdna/aie2_message.c
> +++ b/drivers/accel/amdxdna/aie2_message.c
> @@ -192,6 +192,19 @@ int aie2_query_firmware_version(struct amdxdna_dev_hdl *ndev,
>   	return 0;
>   }
>   
> +static int aie2_destroy_context_req(struct amdxdna_dev_hdl *ndev, u32 id)
> +{
> +	DECLARE_AIE2_MSG(destroy_ctx, MSG_OP_DESTROY_CONTEXT);
> +	struct amdxdna_dev *xdna = ndev->xdna;
> +	int ret;
> +
> +	req.context_id = id;
> +	ret = aie2_send_mgmt_msg_wait(ndev, &msg);
> +	if (ret)
> +		XDNA_WARN(xdna, "Destroy context failed, ret %d", ret);
> +
> +	return ret;
> +}
>   int aie2_create_context(struct amdxdna_dev_hdl *ndev, struct amdxdna_hwctx *hwctx)
>   {
>   	DECLARE_AIE2_MSG(create_ctx, MSG_OP_CREATE_CONTEXT);
> @@ -214,13 +227,16 @@ int aie2_create_context(struct amdxdna_dev_hdl *ndev, struct amdxdna_hwctx *hwct
>   		return ret;
>   
>   	hwctx->fw_ctx_id = resp.context_id;
> -	WARN_ONCE(hwctx->fw_ctx_id == -1, "Unexpected context id");
> +	if (hwctx->fw_ctx_id == -1) {
> +		WARN_ON_ONCE("Unexpected context id");
> +		return -EINVAL;
> +	}

Is the message super important?  I'd think just do this:

if (WARN_ON_ONCE(hwctx->fw_ctx_id == -1))
	return -EINVAL;>
>   	if (ndev->force_preempt_enabled) {
>   		ret = aie2_runtime_cfg(ndev, AIE2_RT_CFG_FORCE_PREEMPT, &hwctx->fw_ctx_id);
>   		if (ret) {
>   			XDNA_ERR(xdna, "failed to enable force preempt %d", ret);
> -			return ret;
> +			goto del_ctx_req;
>   		}
>   	}
>   
> @@ -237,51 +253,39 @@ int aie2_create_context(struct amdxdna_dev_hdl *ndev, struct amdxdna_hwctx *hwct
>   
>   	ret = pci_irq_vector(to_pci_dev(xdna->ddev.dev), resp.msix_id);
>   	if (ret == -EINVAL) {
> -		XDNA_ERR(xdna, "not able to create channel");
> -		goto out_destroy_context;
> +		XDNA_ERR(xdna, "Alloc IRQ failed %d", ret);
> +		goto del_ctx_req;
>   	}
>   
>   	intr_reg = i2x.mb_head_ptr_reg + 4;
>   	hwctx->priv->mbox_chann = xdna_mailbox_create_channel(ndev->mbox, &x2i, &i2x,
>   							      intr_reg, ret);
>   	if (!hwctx->priv->mbox_chann) {
> -		XDNA_ERR(xdna, "not able to create channel");
> +		XDNA_ERR(xdna, "Not able to create channel");
>   		ret = -EINVAL;
> -		goto out_destroy_context;
> +		goto del_ctx_req;
>   	}
>   	ndev->hwctx_num++;
>   
> -	XDNA_DBG(xdna, "%s mailbox channel irq: %d, msix_id: %d",
> -		 hwctx->name, ret, resp.msix_id);
> -	XDNA_DBG(xdna, "%s created fw ctx %d pasid %d", hwctx->name,
> -		 hwctx->fw_ctx_id, hwctx->client->pasid);
> +	XDNA_DBG(xdna, "Mailbox channel irq: %d, msix_id: %d", ret, resp.msix_id);
> +	XDNA_DBG(xdna, "Created fw ctx %d pasid %d", hwctx->fw_ctx_id, hwctx->client->pasid);
>   
>   	return 0;
>   
> -out_destroy_context:
> -	aie2_destroy_context(ndev, hwctx);
> +del_ctx_req:
> +	aie2_destroy_context_req(ndev, hwctx->fw_ctx_id);
>   	return ret;
>   }
>   
>   int aie2_destroy_context(struct amdxdna_dev_hdl *ndev, struct amdxdna_hwctx *hwctx)
>   {
> -	DECLARE_AIE2_MSG(destroy_ctx, MSG_OP_DESTROY_CONTEXT);
>   	struct amdxdna_dev *xdna = ndev->xdna;
>   	int ret;
>   
> -	if (hwctx->fw_ctx_id == -1)
> -		return 0;
> -
>   	xdna_mailbox_stop_channel(hwctx->priv->mbox_chann);
> -
> -	req.context_id = hwctx->fw_ctx_id;
> -	ret = aie2_send_mgmt_msg_wait(ndev, &msg);
> -	if (ret)
> -		XDNA_WARN(xdna, "%s destroy context failed, ret %d", hwctx->name, ret);
> -
> +	ret = aie2_destroy_context_req(ndev, hwctx->fw_ctx_id);
>   	xdna_mailbox_destroy_channel(hwctx->priv->mbox_chann);
> -	XDNA_DBG(xdna, "%s destroyed fw ctx %d", hwctx->name,
> -		 hwctx->fw_ctx_id);
> +	XDNA_DBG(xdna, "Destroyed fw ctx %d", hwctx->fw_ctx_id);
>   	hwctx->priv->mbox_chann = NULL;
>   	hwctx->fw_ctx_id = -1;
>   	ndev->hwctx_num--;