WARNING in batadv_mcast_mla_update

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    eed9688f8513 Merge branch 'ras-core-for-linus' of git://gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10785d57400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=fa5c63e12fd85b25
dashboard link: https://syzkaller.appspot.com/bug?extid=050927a651272b145a5d
compiler:       gcc (GCC) 8.0.1 20180413 (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+050927a651272b145a5d@xxxxxxxxxxxxxxxxxxxxxxxxx

QAT: Invalid ioctl
bond0 (unregistering): Releasing backup interface bond_slave_0
bond0 (unregistering): Released all slaves
WARNING: CPU: 0 PID: 28 at net/batman-adv/multicast.c:371  
batadv_mcast_mla_tt_add net/batman-adv/multicast.c:371 [inline]
WARNING: CPU: 0 PID: 28 at net/batman-adv/multicast.c:371  
__batadv_mcast_mla_update net/batman-adv/multicast.c:636 [inline]
WARNING: CPU: 0 PID: 28 at net/batman-adv/multicast.c:371  
batadv_mcast_mla_update+0x248f/0x2da0 net/batman-adv/multicast.c:661
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 28 Comm: kworker/u4:2 Not tainted 4.20.0+ #390
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+0x1d3/0x2c6 lib/dump_stack.c:113
 panic+0x2ad/0x55c kernel/panic.c:188
 __warn.cold.8+0x20/0x45 kernel/panic.c:540
 report_bug+0x254/0x2d0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271
 do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:290
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:973
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+0x248f/0x2da0  
net/batman-adv/multicast.c:661
Code: 49 c1 ee 03 48 b8 00 00 00 00 00 fc ff df be f8 f8 ff ff 66 41 89 34  
06 48 c1 ea 03 c6 04 02 f8 e9 f7 e7 ff ff e8 41 f3 bf f9 <0f> 0b e9 b8 e3  
ff ff 48 8b bd 48 fc ff ff e8 1e fe 02 fa e9 99 df
RSP: 0018:ffff8880a9fe7338 EFLAGS: 00010293
RAX: ffff8880a9422000 RBX: 0000000000000001 RCX: ffffffff87bf0125
RDX: 0000000000000000 RSI: ffffffff87bf1d6f RDI: 0000000000000007
RBP: ffff8880a9fe7738 R08: ffff8880a9422000 R09: 0000000000000006
R10: 0000000000000000 R11: ffff8880a9422000 R12: ffff8880a9fe7490
R13: 0000000000000000 R14: 1ffff110153fce92 R15: ffff8880a9fe7710
 process_one_work+0xc90/0x1c40 kernel/workqueue.c:2153
 worker_thread+0x17f/0x1390 kernel/workqueue.c:2296
 kthread+0x35a/0x440 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
Kernel Offset: disabled
Rebooting in 86400 seconds..


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