netdev - Re: [PATCH] Bluetooth: L2CAP: fix an illegal state transition from BT

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Date:   Tue, 27 Sep 2022 19:26:28 +0800
From:   kernel test robot <lkp@...el.com>
To:     Sungwoo Kim <iam@...g-woo.kim>
Cc:     llvm@...ts.linux.dev, kbuild-all@...ts.01.org,
        syzkaller@...glegroups.com, Sungwoo Kim <iam@...g-woo.kim>,
        Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        linux-bluetooth@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Bluetooth: L2CAP: fix an illegal state transition from
 BT_DISCONN

Hi Sungwoo,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on bluetooth/master]
[also build test WARNING on bluetooth-next/master linus/master v6.0-rc7 next-20220923]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Sungwoo-Kim/Bluetooth-L2CAP-fix-an-illegal-state-transition-from-BT_DISCONN/20220927-100055
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git master
config: i386-randconfig-a011-20220926
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/c033280cb0996b25511763ada18ac95fa544219f
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Sungwoo-Kim/Bluetooth-L2CAP-fix-an-illegal-state-transition-from-BT_DISCONN/20220927-100055
        git checkout c033280cb0996b25511763ada18ac95fa544219f
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash net/bluetooth/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@...el.com>

All warnings (new ones prefixed by >>):

>> net/bluetooth/l2cap_core.c:4310:6: warning: variable 'err' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
           if (chan->state == BT_DISCONN)
               ^~~~~~~~~~~~~~~~~~~~~~~~~
   net/bluetooth/l2cap_core.c:4346:9: note: uninitialized use occurs here
           return err;
                  ^~~
   net/bluetooth/l2cap_core.c:4310:2: note: remove the 'if' if its condition is always false
           if (chan->state == BT_DISCONN)
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   net/bluetooth/l2cap_core.c:4281:9: note: initialize the variable 'err' to silence this warning
           int err;
                  ^
                   = 0
   1 warning generated.


vim +4310 net/bluetooth/l2cap_core.c

  4272	
  4273	static int l2cap_connect_create_rsp(struct l2cap_conn *conn,
  4274					    struct l2cap_cmd_hdr *cmd, u16 cmd_len,
  4275					    u8 *data)
  4276	{
  4277		struct l2cap_conn_rsp *rsp = (struct l2cap_conn_rsp *) data;
  4278		u16 scid, dcid, result, status;
  4279		struct l2cap_chan *chan;
  4280		u8 req[128];
  4281		int err;
  4282	
  4283		if (cmd_len < sizeof(*rsp))
  4284			return -EPROTO;
  4285	
  4286		scid   = __le16_to_cpu(rsp->scid);
  4287		dcid   = __le16_to_cpu(rsp->dcid);
  4288		result = __le16_to_cpu(rsp->result);
  4289		status = __le16_to_cpu(rsp->status);
  4290	
  4291		BT_DBG("dcid 0x%4.4x scid 0x%4.4x result 0x%2.2x status 0x%2.2x",
  4292		       dcid, scid, result, status);
  4293	
  4294		mutex_lock(&conn->chan_lock);
  4295	
  4296		if (scid) {
  4297			chan = __l2cap_get_chan_by_scid(conn, scid);
  4298			if (!chan) {
  4299				err = -EBADSLT;
  4300				goto unlock;
  4301			}
  4302		} else {
  4303			chan = __l2cap_get_chan_by_ident(conn, cmd->ident);
  4304			if (!chan) {
  4305				err = -EBADSLT;
  4306				goto unlock;
  4307			}
  4308		}
  4309	
> 4310		if (chan->state == BT_DISCONN)
  4311			goto unlock;
  4312	
  4313		err = 0;
  4314	
  4315		l2cap_chan_lock(chan);
  4316	
  4317		switch (result) {
  4318		case L2CAP_CR_SUCCESS:
  4319			l2cap_state_change(chan, BT_CONFIG);
  4320			chan->ident = 0;
  4321			chan->dcid = dcid;
  4322			clear_bit(CONF_CONNECT_PEND, &chan->conf_state);
  4323	
  4324			if (test_and_set_bit(CONF_REQ_SENT, &chan->conf_state))
  4325				break;
  4326	
  4327			l2cap_send_cmd(conn, l2cap_get_ident(conn), L2CAP_CONF_REQ,
  4328				       l2cap_build_conf_req(chan, req, sizeof(req)), req);
  4329			chan->num_conf_req++;
  4330			break;
  4331	
  4332		case L2CAP_CR_PEND:
  4333			set_bit(CONF_CONNECT_PEND, &chan->conf_state);
  4334			break;
  4335	
  4336		default:
  4337			l2cap_chan_del(chan, ECONNREFUSED);
  4338			break;
  4339		}
  4340	
  4341		l2cap_chan_unlock(chan);
  4342	
  4343	unlock:
  4344		mutex_unlock(&conn->chan_lock);
  4345	
  4346		return err;
  4347	}
  4348	

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

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