WARNING in batadv_mcast_mla_update

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 19bb613a Linux 4.19.37
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=130c2870a00000
kernel config: https://syzkaller.appspot.com/x/.config?x=2f4f1677ff80cdff
dashboard link: https://syzkaller.appspot.com/bug?extid=8516c197be291eb99380
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+8516c1...@syzkaller.appspotmail.com

WARNING: CPU: 1 PID: 9643 at net/batman-adv/multicast.c:371
batadv_mcast_mla_tt_add net/batman-adv/multicast.c:371 [inline]
WARNING: CPU: 1 PID: 9643 at net/batman-adv/multicast.c:371
__batadv_mcast_mla_update net/batman-adv/multicast.c:636 [inline]
WARNING: CPU: 1 PID: 9643 at net/batman-adv/multicast.c:371
batadv_mcast_mla_update+0x1927/0x1ec0 net/batman-adv/multicast.c:661
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 9643 Comm: kworker/u4:10 Not tainted 4.19.37 #5
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: bat_events batadv_mcast_mla_update
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
panic+0x263/0x51d kernel/panic.c:185
__warn.cold+0x20/0x54 kernel/panic.c:540
report_bug+0x263/0x2b0 lib/bug.c:186
fixup_bug arch/x86/kernel/traps.c:178 [inline]
fixup_bug arch/x86/kernel/traps.c:173 [inline]
do_error_trap+0x204/0x360 arch/x86/kernel/traps.c:296
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:997
RIP: 0010:batadv_mcast_mla_tt_add net/batman-adv/multicast.c:371 [inline]
RIP: 0010:__batadv_mcast_mla_update net/batman-adv/multicast.c:636 [inline]
RIP: 0010:batadv_mcast_mla_update+0x1927/0x1ec0
net/batman-adv/multicast.c:661
Code: 00 0f 85 95 05 00 00 4c 3b ad d0 fe ff ff 4c 89 ef 4d 8b 65 00 0f 85
a0 fb ff ff e8 63 42 98 fa e9 a6 ef ff ff e8 59 42 98 fa <0f> 0b e9 64 ec
ff ff e8 4d 42 98 fa 8b b5 a8 fe ff ff 31 ff e8 c0
RSP: 0018:ffff88804f427bc0 EFLAGS: 00010293
RAX: ffff88804fb84080 RBX: 0000000000000001 RCX: ffffffff86d2f189
RDX: 0000000000000000 RSI: ffffffff86d30527 RDI: 0000000000000007
RBP: ffff88804f427d30 R08: ffff88804fb84080 R09: ffff88804fb84948
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88804f427c98
R13: ffff88808e131b50 R14: 0000000000000000 R15: ffff88804f427d08
process_one_work+0x98e/0x1760 kernel/workqueue.c:2153
worker_thread+0x98/0xe40 kernel/workqueue.c:2296
kthread+0x357/0x430 kernel/kthread.c:246
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413
Kernel Offset: disabled
Rebooting in 86400 seconds..


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.