linux-kernel - Re: [PATCH] fix null pointer dereferences with a null driver

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Message-ID: <c70ba946-f7bb-6e0f-9fbd-bb57d82ceac2@canonical.com>
Date:   Fri, 8 Sep 2017 14:54:39 +0100
From:   Colin Ian King <colin.king@...onical.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Larry Finger <Larry.Finger@...inger.net>,
        Himanshu Jha <himanshujha199640@...il.com>,
        Ping-Ke Shih <pkshih@...ltek.com>, devel@...verdev.osuosl.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fix null pointer dereferences with a null driver_adapter

On 08/09/17 14:52, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> The call to _rtl_dbg_trace via macro HALMAC_RT_TRACE will trigger a null
> pointer deference on a null driver_adapter.  Fix this by assigning
> driver_adapter earlier to halmac_adapter->driver_adapter before the tracing
> call so that a non-null driver_adapter is passed instead.
> 
> I should have spotted these with an earlier patch I sent, but I overlooked
> these in the rather large CoverityScan logs.
> 
> Detected by CoverityScan, CID#1454550, CID#1454554, CID#1454565,
> CID#1454591, CID#1454598 ("Explicit null dereferenced")
> 
> Fixes: 938a0447f094 ("staging: r8822be: Add code for halmac sub-driver")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  .../staging/rtlwifi/halmac/halmac_88xx/halmac_api_88xx.c    |  4 ++--
>  .../staging/rtlwifi/halmac/halmac_88xx/halmac_func_88xx.c   | 13 +++++++------
>  2 files changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_api_88xx.c b/drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_api_88xx.c
> index 5f84526cb5b5..edbf6af1c8b7 100644
> --- a/drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_api_88xx.c
> +++ b/drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_api_88xx.c
> @@ -2901,11 +2901,11 @@ halmac_update_datapack_88xx(struct halmac_adapter *halmac_adapter,
>  	if (halmac_adapter->fw_version.h2c_version < 4)
>  		return HALMAC_RET_FW_NO_SUPPORT;
>  
> +	driver_adapter = halmac_adapter->driver_adapter;
> +
>  	HALMAC_RT_TRACE(driver_adapter, HALMAC_MSG_H2C, DBG_DMESG,
>  			"[TRACE]%s ==========>\n", __func__);
>  
> -	driver_adapter = halmac_adapter->driver_adapter;
> -
>  	HALMAC_RT_TRACE(driver_adapter, HALMAC_MSG_H2C, DBG_DMESG,
>  			"[TRACE]%s <==========\n", __func__);
>  
> diff --git a/drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_func_88xx.c b/drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_func_88xx.c
> index f33024e4d853..544f638ed3ef 100644
> --- a/drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_func_88xx.c
> +++ b/drivers/staging/rtlwifi/halmac/halmac_88xx/halmac_func_88xx.c
> @@ -1618,10 +1618,11 @@ halmac_send_h2c_set_pwr_mode_88xx(struct halmac_adapter *halmac_adapter,
>  	void *driver_adapter = NULL;
>  	enum halmac_ret_status status = HALMAC_RET_SUCCESS;
>  
> +	driver_adapter = halmac_adapter->driver_adapter;
> +
>  	HALMAC_RT_TRACE(driver_adapter, HALMAC_MSG_H2C, DBG_DMESG,
>  			"%s!!\n", __func__);
>  
> -	driver_adapter = halmac_adapter->driver_adapter;
>  	h2c_header = h2c_buff;
>  	h2c_cmd = h2c_header + HALMAC_H2C_CMD_HDR_SIZE_88XX;
>  
> @@ -1713,10 +1714,11 @@ halmac_media_status_rpt_88xx(struct halmac_adapter *halmac_adapter, u8 op_mode,
>  	void *driver_adapter = NULL;
>  	enum halmac_ret_status status = HALMAC_RET_SUCCESS;
>  
> +	driver_adapter = halmac_adapter->driver_adapter;
> +
>  	HALMAC_RT_TRACE(driver_adapter, HALMAC_MSG_H2C, DBG_DMESG,
>  			"halmac_send_h2c_set_pwr_mode_88xx!!\n");
>  
> -	driver_adapter = halmac_adapter->driver_adapter;
>  	h2c_header = H2c_buff;
>  	h2c_cmd = h2c_header + HALMAC_H2C_CMD_HDR_SIZE_88XX;
>  
> @@ -2143,10 +2145,11 @@ halmac_func_ctrl_ch_switch_88xx(struct halmac_adapter *halmac_adapter,
>  	enum halmac_cmd_process_status *process_status =
>  		&halmac_adapter->halmac_state.scan_state_set.process_status;
>  
> +	driver_adapter = halmac_adapter->driver_adapter;
> +
>  	HALMAC_RT_TRACE(driver_adapter, HALMAC_MSG_H2C, DBG_DMESG,
>  			"halmac_ctrl_ch_switch!!\n");
>  
> -	driver_adapter = halmac_adapter->driver_adapter;
>  	halmac_api = (struct halmac_api *)halmac_adapter->halmac_api;
>  
>  	if (halmac_transition_scan_state_88xx(
> @@ -2276,15 +2279,13 @@ enum halmac_ret_status halmac_send_h2c_update_bcn_parse_info_88xx(
>  {
>  	u8 h2c_buff[HALMAC_H2C_CMD_SIZE_88XX] = {0};
>  	u16 h2c_seq_mum = 0;
> -	void *driver_adapter = NULL;
> +	void *driver_adapter = halmac_adapter->driver_adapter;
>  	struct halmac_h2c_header_info h2c_header_info;
>  	enum halmac_ret_status status = HALMAC_RET_SUCCESS;
>  
>  	HALMAC_RT_TRACE(driver_adapter, HALMAC_MSG_H2C, DBG_DMESG,
>  			"%s!!\n", __func__);
>  
> -	driver_adapter = halmac_adapter->driver_adapter;
> -
>  	UPDATE_BEACON_PARSING_INFO_SET_FUNC_EN(h2c_buff, bcn_ie_info->func_en);
>  	UPDATE_BEACON_PARSING_INFO_SET_SIZE_TH(h2c_buff, bcn_ie_info->size_th);
>  	UPDATE_BEACON_PARSING_INFO_SET_TIMEOUT(h2c_buff, bcn_ie_info->timeout);
> 

Oops, I messed up the subject line, will resend V2.