linux-kernel - [hverkuil-media-tree:fix-cec 1/5] drivers/media/cec/core/cec-pin.c:1291 cec_pin_adap_free() warn: variable dereferenced before check 'pin' (see line 1288)

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Date:   Mon, 9 May 2022 14:00:55 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     kbuild@...ts.01.org, Hans Verkuil <hverkuil@...all.nl>
Cc:     lkp@...el.com, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org
Subject: [hverkuil-media-tree:fix-cec 1/5]
 drivers/media/cec/core/cec-pin.c:1291 cec_pin_adap_free() warn: variable
 dereferenced before check 'pin' (see line 1288)

tree:   git://linuxtv.org/hverkuil/media_tree.git fix-cec
head:   dd36bee1793249cb2548e9a4b6c10a079a10037d
commit: bb541e5dcec111915f565b0cf8c3313f38bd72d8 [1/5] cec-pin: disabling the adapter cannot call kthread_stop
config: openrisc-randconfig-m031-20220506 (https://download.01.org/0day-ci/archive/20220508/202205081847.EPfgN3uq-lkp@intel.com/config)
compiler: or1k-linux-gcc (GCC) 11.3.0

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>

smatch warnings:
drivers/media/cec/core/cec-pin.c:1291 cec_pin_adap_free() warn: variable dereferenced before check 'pin' (see line 1288)

vim +/pin +1291 drivers/media/cec/core/cec-pin.c

ea5c8ef296681b drivers/media/cec/cec-pin.c      Hans Verkuil 2017-07-11  1284  static void cec_pin_adap_free(struct cec_adapter *adap)
ea5c8ef296681b drivers/media/cec/cec-pin.c      Hans Verkuil 2017-07-11  1285  {
ea5c8ef296681b drivers/media/cec/cec-pin.c      Hans Verkuil 2017-07-11  1286  	struct cec_pin *pin = adap->pin;
ea5c8ef296681b drivers/media/cec/cec-pin.c      Hans Verkuil 2017-07-11  1287  
bb541e5dcec111 drivers/media/cec/core/cec-pin.c Hans Verkuil 2022-05-06 @1288  	if (pin->kthread)
                                                                                    ^^^^^
Dereference

bb541e5dcec111 drivers/media/cec/core/cec-pin.c Hans Verkuil 2022-05-06  1289  		kthread_stop(pin->kthread);
bb541e5dcec111 drivers/media/cec/core/cec-pin.c Hans Verkuil 2022-05-06  1290  	pin->kthread = NULL;
e2ed5024ac2bc2 drivers/media/cec/core/cec-pin.c Hans Verkuil 2022-03-17 @1291  	if (pin && pin->ops->free)
                                                                                    ^^^
Checked too late

ea5c8ef296681b drivers/media/cec/cec-pin.c      Hans Verkuil 2017-07-11  1292  		pin->ops->free(adap);
ea5c8ef296681b drivers/media/cec/cec-pin.c      Hans Verkuil 2017-07-11  1293  	adap->pin = NULL;
ea5c8ef296681b drivers/media/cec/cec-pin.c      Hans Verkuil 2017-07-11  1294  	kfree(pin);
ea5c8ef296681b drivers/media/cec/cec-pin.c      Hans Verkuil 2017-07-11  1295  }

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp