WARNING in kcov_remote_start (3)

Status: upstream: reported on 2026/07/10 20:40
Reported-by: syzbot+68789761f4413821b77b@syzkaller.appspotmail.com
First crash: 18d, last: 18d
Similar bugs (10)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 WARNING in kcov_remote_start (2) -1 1 153d 153d 0/3 auto-obsoleted due to no activity on 2026/06/06 04:25
linux-5.15 WARNING in kcov_remote_start -1 4 565d 665d 0/3 auto-obsoleted due to no activity on 2025/04/19 19:40
linux-6.6 WARNING in kcov_remote_start -1 1 68d 68d 0/2 upstream: reported on 2026/05/22 01:58
upstream WARNING in kcov_remote_start (4) usb -1 107983 749d 779d 26/29 fixed on 2024/07/10 08:24
upstream WARNING in kcov_remote_start (2) usb -1 syz, C 1153 2520d 2520d 0/29 closed as invalid on 2019/09/04 14:27
upstream WARNING in kcov_remote_start (5) wireless -1 4243 645d 745d 28/29 fixed on 2024/10/22 14:56
upstream WARNING in kcov_remote_start (3) usb -1 265513 783d 853d 25/29 fixed on 2024/06/05 13:52
upstream WARNING in kcov_remote_start usb -1 syz, C 655 2520d 2520d 0/29 closed as invalid on 2019/09/03 16:37
upstream WARNING in kcov_remote_start (6) kernel prio:low -1 40461 now 631d 2/29 upstream: reported on 2024/11/04 21:25
linux-6.1 WARNING in kcov_remote_start -1 13 39d 395d 0/3 upstream: reported on 2025/06/28 15:34

Sample crash report:
netlink: 'syz.2.2418': attribute type 10 has an invalid length.
team0: Device wlan1 is of different type
------------[ cut here ]------------
WARNING: CPU: 0 PID: 12386 at kernel/kcov.c:844 __refcount_sub_and_test include/linux/refcount.h:283 [inline]
WARNING: CPU: 0 PID: 12386 at kernel/kcov.c:844 __refcount_dec_and_test include/linux/refcount.h:315 [inline]
WARNING: CPU: 0 PID: 12386 at kernel/kcov.c:844 refcount_dec_and_test include/linux/refcount.h:333 [inline]
WARNING: CPU: 0 PID: 12386 at kernel/kcov.c:844 kcov_put kernel/kcov.c:415 [inline]
WARNING: CPU: 0 PID: 12386 at kernel/kcov.c:844 kcov_remote_start+0x36a/0x490 kernel/kcov.c:888
Modules linked in:
CPU: 0 PID: 12386 Comm: syz.2.2418 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:kcov_remote_start+0x36a/0x490 kernel/kcov.c:844
Code: e8 5b b0 39 00 4c 89 ff e8 43 7f 44 00 e9 ac fd ff ff 0f 8d a6 fd ff ff 4c 89 ff be 03 00 00 00 e8 8b 14 6f 02 e9 94 fd ff ff <0f> 0b 41 f7 c6 00 02 00 00 74 05 e8 56 1b 06 00 48 c7 04 24 00 00
RSP: 0000:ffffc90002ebe0b8 EFLAGS: 00010002
RAX: 0000000080000200 RBX: ffff888074389dc0 RCX: 0000000000080001
RDX: ffffc900042c4000 RSI: 000000000005f052 RDI: 0000000000000000
RBP: ffffc90002ebe310 R08: ffff888074389dc0 R09: 0000000000000004
R10: 0000000000000003 R11: 0000000000000002 R12: ffff8880740b8e00
R13: ffff88802515cdc0 R14: 0000000000000246 R15: 0000000000000000
FS:  00007f10051e76c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe79695e8f0 CR3: 000000007e03b000 CR4: 00000000003506f0
DR0: 0000000000000008 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 kcov_remote_start_common include/linux/kcov.h:50 [inline]
 ieee80211_rx_list+0x5e4/0x25e0 net/mac80211/rx.c:4977
 ieee80211_rx_napi+0x17f/0x390 net/mac80211/rx.c:5018
 ieee80211_rx include/net/mac80211.h:4573 [inline]
 ieee80211_handle_queued_frames+0x104/0x1a0 net/mac80211/main.c:237
 ieee80211_stop_device+0x16/0x80 net/mac80211/util.c:2150
 ieee80211_do_stop+0x1653/0x1d30 net/mac80211/iface.c:639
 ieee80211_stop+0x127/0x190 net/mac80211/iface.c:667
 __dev_close_many+0x1d3/0x2b0 net/core/dev.c:1634
 dev_close_many+0x21c/0x400 net/core/dev.c:1659
 dev_close+0x154/0x210 net/core/dev.c:1685
 team_port_add drivers/net/team/team.c:1324 [inline]
 team_add_slave+0x1711/0x2840 drivers/net/team/team.c:1997
 do_set_master net/core/rtnetlink.c:2581 [inline]
 do_setlink+0xe79/0x29d0 net/core/rtnetlink.c:2792
 __rtnl_newlink net/core/rtnetlink.c:3456 [inline]
 rtnl_newlink+0x15bb/0x1920 net/core/rtnetlink.c:3578
 rtnetlink_rcv_msg+0x82c/0xf00 net/core/rtnetlink.c:5688
 netlink_rcv_skb+0x1e9/0x430 net/netlink/af_netlink.c:2512
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x78f/0x940 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1923
 sock_sendmsg_nosec net/socket.c:706 [inline]
 __sock_sendmsg net/socket.c:718 [inline]
 ____sys_sendmsg+0x5be/0x8f0 net/socket.c:2446
 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2500
 __sys_sendmsg net/socket.c:2529 [inline]
 __do_sys_sendmsg net/socket.c:2538 [inline]
 __se_sys_sendmsg+0x1b7/0x2a0 net/socket.c:2536
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f1006f8ee59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f10051e7028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f1007216fa0 RCX: 00007f1006f8ee59
RDX: 0000000000000000 RSI: 0000200000000600 RDI: 000000000000000d
RBP: 00007f1007024e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1007217038 R14: 00007f1007216fa0 R15: 00007ffc40a98d98
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/10 20:39 linux-5.15.y c86c4726e7f0 99e64375 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf WARNING in kcov_remote_start
* Struck through repros no longer work on HEAD.