====================================================== WARNING: possible circular locking dependency detected 4.19.211-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.0/23868 is trying to acquire lock: 00000000c2670349 (&p->lock){+.+.}, at: seq_read+0x6b/0x11c0 fs/seq_file.c:164 but task is already holding lock: 0000000087ce14a0 (sb_writers#3){.+.+}, at: file_start_write include/linux/fs.h:2779 [inline] 0000000087ce14a0 (sb_writers#3){.+.+}, at: do_sendfile+0x97d/0xc30 fs/read_write.c:1446 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (sb_writers#3){.+.+}: sb_start_write include/linux/fs.h:1579 [inline] mnt_want_write+0x3a/0xb0 fs/namespace.c:360 ovl_create_object+0x96/0x290 fs/overlayfs/dir.c:602 lookup_open+0x893/0x1a20 fs/namei.c:3235 do_last fs/namei.c:3327 [inline] path_openat+0x1094/0x2df0 fs/namei.c:3537 do_filp_open+0x18c/0x3f0 fs/namei.c:3567 do_sys_open+0x3b3/0x520 fs/open.c:1085 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (&ovl_i_mutex_dir_key[depth]){++++}: inode_lock_shared include/linux/fs.h:758 [inline] do_last fs/namei.c:3326 [inline] path_openat+0x17ec/0x2df0 fs/namei.c:3537 do_filp_open+0x18c/0x3f0 fs/namei.c:3567 do_open_execat+0x11d/0x5b0 fs/exec.c:853 __do_execve_file+0x1a8b/0x2360 fs/exec.c:1770 do_execveat_common fs/exec.c:1879 [inline] do_execve+0x35/0x50 fs/exec.c:1896 __do_sys_execve fs/exec.c:1977 [inline] __se_sys_execve fs/exec.c:1972 [inline] __x64_sys_execve+0x7c/0xa0 fs/exec.c:1972 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (&sig->cred_guard_mutex){+.+.}: lock_trace fs/proc/base.c:402 [inline] proc_pid_syscall+0xb8/0x2f0 fs/proc/base.c:635 proc_single_show+0xeb/0x170 fs/proc/base.c:755 seq_read+0x4e0/0x11c0 fs/seq_file.c:232 __vfs_read+0xf7/0x750 fs/read_write.c:416 vfs_read+0x194/0x3c0 fs/read_write.c:452 ksys_read+0x12b/0x2a0 fs/read_write.c:579 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&p->lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:937 [inline] __mutex_lock+0xd7/0x1190 kernel/locking/mutex.c:1078 seq_read+0x6b/0x11c0 fs/seq_file.c:164 proc_reg_read+0x1bd/0x2d0 fs/proc/inode.c:231 do_loop_readv_writev fs/read_write.c:701 [inline] do_loop_readv_writev fs/read_write.c:688 [inline] do_iter_read+0x471/0x630 fs/read_write.c:925 vfs_readv+0xe5/0x150 fs/read_write.c:987 kernel_readv fs/splice.c:362 [inline] default_file_splice_read+0x457/0xa00 fs/splice.c:417 do_splice_to+0x10e/0x160 fs/splice.c:881 splice_direct_to_actor+0x2b9/0x8d0 fs/splice.c:959 do_splice_direct+0x1a7/0x270 fs/splice.c:1068 do_sendfile+0x550/0xc30 fs/read_write.c:1447 __do_sys_sendfile64 fs/read_write.c:1508 [inline] __se_sys_sendfile64+0x147/0x160 fs/read_write.c:1494 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: &p->lock --> &ovl_i_mutex_dir_key[depth] --> sb_writers#3 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sb_writers#3); lock(&ovl_i_mutex_dir_key[depth]); lock(sb_writers#3); lock(&p->lock); *** DEADLOCK *** 1 lock held by syz-executor.0/23868: #0: 0000000087ce14a0 (sb_writers#3){.+.+}, at: file_start_write include/linux/fs.h:2779 [inline] #0: 0000000087ce14a0 (sb_writers#3){.+.+}, at: do_sendfile+0x97d/0xc30 fs/read_write.c:1446 stack backtrace: CPU: 1 PID: 23868 Comm: syz-executor.0 Not tainted 4.19.211-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fc/0x2ef lib/dump_stack.c:118 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1222 check_prev_add kernel/locking/lockdep.c:1866 [inline] check_prevs_add kernel/locking/lockdep.c:1979 [inline] validate_chain kernel/locking/lockdep.c:2420 [inline] __lock_acquire+0x30c9/0x3ff0 kernel/locking/lockdep.c:3416 lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3908 __mutex_lock_common kernel/locking/mutex.c:937 [inline] __mutex_lock+0xd7/0x1190 kernel/locking/mutex.c:1078 seq_read+0x6b/0x11c0 fs/seq_file.c:164 proc_reg_read+0x1bd/0x2d0 fs/proc/inode.c:231 do_loop_readv_writev fs/read_write.c:701 [inline] do_loop_readv_writev fs/read_write.c:688 [inline] do_iter_read+0x471/0x630 fs/read_write.c:925 vfs_readv+0xe5/0x150 fs/read_write.c:987 kernel_readv fs/splice.c:362 [inline] default_file_splice_read+0x457/0xa00 fs/splice.c:417 do_splice_to+0x10e/0x160 fs/splice.c:881 splice_direct_to_actor+0x2b9/0x8d0 fs/splice.c:959 do_splice_direct+0x1a7/0x270 fs/splice.c:1068 do_sendfile+0x550/0xc30 fs/read_write.c:1447 __do_sys_sendfile64 fs/read_write.c:1508 [inline] __se_sys_sendfile64+0x147/0x160 fs/read_write.c:1494 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f32aacea209 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f32a965f168 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00007f32aadfcf60 RCX: 00007f32aacea209 RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000003 RBP: 00007f32aad44161 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000009 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffcc8072cdf R14: 00007f32a965f300 R15: 0000000000022000 encrypted_key: master key parameter 'tr0000000¡DI©04096' is invalid caif:caif_disconnect_client(): nothing to disconnect encrypted_key: master key parameter 'tr0000000¡DI©04096' is invalid caif:caif_disconnect_client(): nothing to disconnect audit: type=1804 audit(1659356582.419:164): pid=23948 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.3" name="/root/syzkaller-testdir2250904659/syzkaller.eSCRIu/329/bus" dev="sda1" ino=14370 res=1 encrypted_key: master key parameter 'tr0000000¡DI©04096' is invalid encrypted_key: master key parameter 'tr0000000¡DI©04096' is invalid audit: type=1804 audit(1659356582.489:165): pid=23954 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=ToMToU comm="syz-executor.3" name="/root/syzkaller-testdir2250904659/syzkaller.eSCRIu/329/bus" dev="sda1" ino=14370 res=1 audit: type=1804 audit(1659356582.499:166): pid=23954 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=ToMToU comm="syz-executor.3" name="/root/syzkaller-testdir2250904659/syzkaller.eSCRIu/329/bus" dev="sda1" ino=14370 res=1 EXT4-fs: failed to create workqueue EXT4-fs (loop4): mount failed caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect EXT4-fs (loop4): mounted filesystem without journal. Opts: ,errors=continue caif:caif_disconnect_client(): nothing to disconnect netlink: 'syz-executor.0': attribute type 10 has an invalid length. netlink: 'syz-executor.0': attribute type 10 has an invalid length. caif:caif_disconnect_client(): nothing to disconnect netlink: 'syz-executor.0': attribute type 10 has an invalid length. IPVS: ftp: loaded support on port[0] = 21 netlink: 'syz-executor.0': attribute type 10 has an invalid length. caif:caif_disconnect_client(): nothing to disconnect audit: type=1804 audit(1659356583.349:167): pid=24064 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.3" name="/root/syzkaller-testdir2250904659/syzkaller.eSCRIu/330/bus" dev="sda1" ino=15062 res=1 netlink: 'syz-executor.0': attribute type 10 has an invalid length. caif:caif_disconnect_client(): nothing to disconnect audit: type=1804 audit(1659356583.389:168): pid=24062 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=ToMToU comm="syz-executor.3" name="/root/syzkaller-testdir2250904659/syzkaller.eSCRIu/330/bus" dev="sda1" ino=15062 res=1 audit: type=1804 audit(1659356583.389:169): pid=24062 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=ToMToU comm="syz-executor.3" name="/root/syzkaller-testdir2250904659/syzkaller.eSCRIu/330/bus" dev="sda1" ino=15062 res=1 audit: type=1804 audit(1659356583.389:170): pid=24062 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=ToMToU comm="syz-executor.3" name="/root/syzkaller-testdir2250904659/syzkaller.eSCRIu/330/bus" dev="sda1" ino=15062 res=1 audit: type=1804 audit(1659356583.389:171): pid=24062 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=ToMToU comm="syz-executor.3" name="/root/syzkaller-testdir2250904659/syzkaller.eSCRIu/330/bus" dev="sda1" ino=15062 res=1 caif:caif_disconnect_client(): nothing to disconnect IPVS: ftp: loaded support on port[0] = 21 caif:caif_disconnect_client(): nothing to disconnect audit: type=1804 audit(1659356583.399:172): pid=24062 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=ToMToU comm="syz-executor.3" name="/root/syzkaller-testdir2250904659/syzkaller.eSCRIu/330/bus" dev="sda1" ino=15062 res=1 IPVS: ftp: loaded support on port[0] = 21 FAT-fs (loop2): Unrecognized mount option "fmask=0000000000" or missing value audit: type=1804 audit(1659356583.399:173): pid=24062 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=ToMToU comm="syz-executor.3" name="/root/syzkaller-testdir2250904659/syzkaller.eSCRIu/330/bus" dev="sda1" ino=15062 res=1 IPVS: ftp: loaded support on port[0] = 21 caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect EXT4-fs warning (device sda1): verify_group_input:131: Cannot add at group 8 (only 16 groups) FAT-fs (loop2): Unrecognized mount option "fmask=0000000000" or missing value caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect EXT4-fs warning (device sda1): verify_group_input:131: Cannot add at group 8 (only 16 groups) caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect ieee80211 ©,í…×;qO!: Selected rate control algorithm 'minstrel_ht' caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect sysfs: cannot create duplicate filename '/class/ieee80211/©,í…×;qO!' CPU: 0 PID: 24588 Comm: syz-executor.2 Not tainted 4.19.211-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fc/0x2ef lib/dump_stack.c:118 sysfs_warn_dup.cold+0x1c/0x29 fs/sysfs/dir.c:30 sysfs_do_create_link_sd+0x116/0x130 fs/sysfs/symlink.c:50 sysfs_do_create_link fs/sysfs/symlink.c:79 [inline] sysfs_create_link+0x5f/0xc0 fs/sysfs/symlink.c:91 device_add_class_symlinks drivers/base/core.c:1934 [inline] device_add+0x7d1/0x16d0 drivers/base/core.c:2136 wiphy_register+0x1664/0x2130 net/wireless/core.c:832 ieee80211_register_hw+0x13be/0x3550 net/mac80211/main.c:1106 mac80211_hwsim_new_radio+0x1d3f/0x3c60 drivers/net/wireless/mac80211_hwsim.c:2896 hwsim_new_radio_nl+0x5c3/0x850 drivers/net/wireless/mac80211_hwsim.c:3374 genl_family_rcv_msg+0x642/0xc40 net/netlink/genetlink.c:602 genl_rcv_msg+0xbf/0x160 net/netlink/genetlink.c:627 netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2463 genl_rcv+0x24/0x40 net/netlink/genetlink.c:638 netlink_unicast_kernel net/netlink/af_netlink.c:1325 [inline] netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1351 netlink_sendmsg+0x6c3/0xc50 net/netlink/af_netlink.c:1917 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xc3/0x120 net/socket.c:661 ___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2227 __sys_sendmsg net/socket.c:2265 [inline] __do_sys_sendmsg net/socket.c:2274 [inline] __se_sys_sendmsg net/socket.c:2272 [inline] __x64_sys_sendmsg+0x132/0x220 net/socket.c:2272 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7fbed837e209 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fbed6cf3168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fbed8490f60 RCX: 00007fbed837e209 RDX: 0000000000000000 RSI: 0000000020000400 RDI: 0000000000000004 RBP: 00007fbed83d8161 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffc6db1145f R14: 00007fbed6cf3300 R15: 0000000000022000 caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect kauditd_printk_skb: 31 callbacks suppressed audit: type=1800 audit(1659356588.600:205): pid=24628 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="syz-executor.0" name="file0" dev="sda1" ino=15054 res=0 sysfs: cannot create duplicate filename '/class/ieee80211/©,í…×;qO!' audit: type=1804 audit(1659356588.610:206): pid=24628 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.0" name="/root/syzkaller-testdir2015451643/syzkaller.05OKms/337/file0" dev="sda1" ino=15054 res=1 CPU: 1 PID: 24635 Comm: syz-executor.2 Not tainted 4.19.211-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fc/0x2ef lib/dump_stack.c:118 sysfs_warn_dup.cold+0x1c/0x29 fs/sysfs/dir.c:30 sysfs_do_create_link_sd+0x116/0x130 fs/sysfs/symlink.c:50 sysfs_do_create_link fs/sysfs/symlink.c:79 [inline] sysfs_create_link+0x5f/0xc0 fs/sysfs/symlink.c:91 audit: type=1804 audit(1659356588.610:207): pid=24628 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=ToMToU comm="syz-executor.0" name="/root/syzkaller-testdir2015451643/syzkaller.05OKms/337/file0" dev="sda1" ino=15054 res=1 device_add_class_symlinks drivers/base/core.c:1934 [inline] device_add+0x7d1/0x16d0 drivers/base/core.c:2136 wiphy_register+0x1664/0x2130 net/wireless/core.c:832 ieee80211_register_hw+0x13be/0x3550 net/mac80211/main.c:1106 mac80211_hwsim_new_radio+0x1d3f/0x3c60 drivers/net/wireless/mac80211_hwsim.c:2896 hwsim_new_radio_nl+0x5c3/0x850 drivers/net/wireless/mac80211_hwsim.c:3374 genl_family_rcv_msg+0x642/0xc40 net/netlink/genetlink.c:602 genl_rcv_msg+0xbf/0x160 net/netlink/genetlink.c:627 netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2463 genl_rcv+0x24/0x40 net/netlink/genetlink.c:638 netlink_unicast_kernel net/netlink/af_netlink.c:1325 [inline] netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1351 netlink_sendmsg+0x6c3/0xc50 net/netlink/af_netlink.c:1917 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xc3/0x120 net/socket.c:661 ___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2227 __sys_sendmsg net/socket.c:2265 [inline] __do_sys_sendmsg net/socket.c:2274 [inline] __se_sys_sendmsg net/socket.c:2272 [inline] __x64_sys_sendmsg+0x132/0x220 net/socket.c:2272 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7fbed837e209 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fbed6cf3168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fbed8490f60 RCX: 00007fbed837e209 RDX: 0000000000000000 RSI: 0000000020000400 RDI: 0000000000000004 RBP: 00007fbed83d8161 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffc6db1145f R14: 00007fbed6cf3300 R15: 0000000000022000 caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect audit: type=1800 audit(1659356589.520:208): pid=24690 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="syz-executor.1" name="file0" dev="sda1" ino=15088 res=0 audit: type=1800 audit(1659356589.540:209): pid=24700 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="syz-executor.0" name="file0" dev="sda1" ino=14561 res=0 REISERFS warning (device loop1): super-6510 reiserfs_parse_options: journal device was already specified to be ./file0 audit: type=1804 audit(1659356589.540:210): pid=24699 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.0" name="/root/syzkaller-testdir2015451643/syzkaller.05OKms/338/file0" dev="sda1" ino=14561 res=1 audit: type=1804 audit(1659356589.540:211): pid=24700 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=ToMToU comm="syz-executor.0" name="/root/syzkaller-testdir2015451643/syzkaller.05OKms/338/file0" dev="sda1" ino=14561 res=1 caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect audit: type=1800 audit(1659356589.860:212): pid=24730 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="syz-executor.0" name="file0" dev="sda1" ino=15100 res=0 audit: type=1804 audit(1659356589.870:213): pid=24731 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.0" name="/root/syzkaller-testdir2015451643/syzkaller.05OKms/339/file0" dev="sda1" ino=15100 res=1 audit: type=1804 audit(1659356589.870:214): pid=24731 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.0" name="/root/syzkaller-testdir2015451643/syzkaller.05OKms/339/file0" dev="sda1" ino=15100 res=1 caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect caif:caif_disconnect_client(): nothing to disconnect