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

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Date:   Fri,  8 Sep 2017 14:52:22 +0100
From:   Colin 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: [PATCH] fix null pointer dereferences with a null driver_adapter

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);
-- 
2.14.1