linux-kernel - Re: [ammarfaizi2-block:kvalo/ath/pending 36/40] drivers/net/wireless/ath/ath11k/mac.c:8293 ath11k_mac_op_set_bios_sar_specs() warn: variable dereferenced before check 'sar' (see line 8280)

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Date:   Wed, 27 Apr 2022 19:55:08 +0800
From:   Baochen Qiang <quic_bqiang@...cinc.com>
To:     Kalle Valo <quic_kvalo@...cinc.com>,
        Dan Carpenter <dan.carpenter@...cle.com>
CC:     <kbuild@...ts.01.org>, <lkp@...el.com>, <kbuild-all@...ts.01.org>,
        GNU/Weeb Mailing List <gwml@...r.gnuweeb.org>,
        <linux-kernel@...r.kernel.org>, <ath11k@...ts.infradead.org>
Subject: Re: [ammarfaizi2-block:kvalo/ath/pending 36/40]
 drivers/net/wireless/ath/ath11k/mac.c:8293 ath11k_mac_op_set_bios_sar_specs()
 warn: variable dereferenced before check 'sar' (see line 8280)


On 4/27/2022 7:19 PM, Kalle Valo wrote:
> + ath11k list
>
> Dan Carpenter <dan.carpenter@...cle.com> writes:
>
>> tree:   https://github.com/ammarfaizi2/linux-block kvalo/ath/pending
>> head:   c9a8efc35304a89fc0751649945909caf03eeb29
>> commit: 5ad5b356e75f402fec930cf0d77b6c7862850b55 [36/40] ath11k: Add support for SAR
>> config: x86_64-randconfig-m001-20220418 (https://download.01.org/0day-ci/archive/20220418/202204182315.h96VPgso-lkp@intel.com/config)
>> compiler: gcc-11 (Debian 11.2.0-19) 11.2.0
>>
>> If you fix the issue, kindly add following tag as appropriate
>> Reported-by: kernel test robot <lkp@...el.com>
>> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
>>
>> New smatch warnings:
>> drivers/net/wireless/ath/ath11k/mac.c:8293 ath11k_mac_op_set_bios_sar_specs() warn: variable dereferenced before check 'sar' (see line 8280)
>>
>> vim +/sar +8293 drivers/net/wireless/ath/ath11k/mac.c
>>
>> 5ad5b356e75f40 Baochen Qiang 2022-04-12  8276  static int ath11k_mac_op_set_bios_sar_specs(struct ieee80211_hw *hw,
>> 5ad5b356e75f40 Baochen Qiang 2022-04-12  8277  					    const struct cfg80211_sar_specs *sar)
>> 5ad5b356e75f40 Baochen Qiang 2022-04-12  8278  {
>> 5ad5b356e75f40 Baochen Qiang 2022-04-12  8279  	struct ath11k *ar = hw->priv;
>> 5ad5b356e75f40 Baochen Qiang 2022-04-12 @8280  	const struct cfg80211_sar_sub_specs *sspec = sar->sub_specs;
>>                                                                                               ^^^^^^^^^^^^^^
>> Dereference
>>
>> 5ad5b356e75f40 Baochen Qiang 2022-04-12  8281  	int ret, index;
>> 5ad5b356e75f40 Baochen Qiang 2022-04-12  8282  	u8 *sar_tbl;
>> 5ad5b356e75f40 Baochen Qiang 2022-04-12  8283  	u32 i;
>> 5ad5b356e75f40 Baochen Qiang 2022-04-12  8284
>> 5ad5b356e75f40 Baochen Qiang 2022-04-12  8285  	mutex_lock(&ar->conf_mutex);
>> 5ad5b356e75f40 Baochen Qiang 2022-04-12  8286
>> 5ad5b356e75f40 Baochen Qiang 2022-04-12  8287  	if (!test_bit(WMI_TLV_SERVICE_BIOS_SAR_SUPPORT, ar->ab->wmi_ab.svc_map) ||
>> 5ad5b356e75f40 Baochen Qiang 2022-04-12  8288  	    !ar->ab->hw_params.bios_sar_capa) {
>> 5ad5b356e75f40 Baochen Qiang 2022-04-12  8289  		ret = -EOPNOTSUPP;
>> 5ad5b356e75f40 Baochen Qiang 2022-04-12  8290  		goto exit;
>> 5ad5b356e75f40 Baochen Qiang 2022-04-12  8291  	}
>> 5ad5b356e75f40 Baochen Qiang 2022-04-12  8292
>> 5ad5b356e75f40 Baochen Qiang 2022-04-12 @8293  	if (!sar || sar->type != NL80211_SAR_TYPE_POWER ||
>>                                                       ^^^
>> Checked too late
> Baochen, please submit a fix for this.

Sure, Kalle. I just sent the fix patch named "ath11k: Fix warning on 
variable 'sar' dereference before check" to internal review.