general protection fault in batadv_iv_ogm_schedule_buff

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: c10b57a5 Linux 4.14.176
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1303df77e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=457897b554d08537
dashboard link: https://syzkaller.appspot.com/bug?extid=d04a9278e74682f55d80
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+d04a92...@syzkaller.appspotmail.com

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 7681 Comm: kworker/u4:6 Not tainted 4.14.176-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
task: ffff888098040040 task.stack: ffff88804fee8000
RIP: 0010:batadv_iv_ogm_schedule_buff+0x9ca/0xeb0 net/batman-adv/bat_iv_ogm.c:1015
RSP: 0018:ffff88804feefc40 EFLAGS: 00010202
RAX: 000000000000000e RBX: 0000000000000000 RCX: 1ffff11013008126
RDX: 0000000000000000 RSI: ffff888098040938 RDI: 0000000000000070
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
R13: ffff8880868c6030 R14: ffffed101153a00e R15: ffff88808a9d0000
FS: 0000000000000000(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000004d8770 CR3: 0000000096845000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
batadv_iv_ogm_schedule net/batman-adv/bat_iv_ogm.c:1041 [inline]
batadv_iv_ogm_schedule net/batman-adv/bat_iv_ogm.c:1034 [inline]
batadv_iv_send_outstanding_bat_ogm_packet+0x500/0x6f0 net/batman-adv/bat_iv_ogm.c:1859
process_one_work+0x813/0x1540 kernel/workqueue.c:2116
worker_thread+0x5d1/0x1070 kernel/workqueue.c:2250
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Code: 42 80 3c 20 00 0f 85 18 04 00 00 48 8b 1b 48 81 fb 40 4f 06 8b 0f 84 2f 01 00 00 e8 51 2b 35 fb 48 8d 7b 70 48 89 f8 48 c1 e8 03 <42> 80 3c 20 00 0f 85 fa 03 00 00 41 80 3e 00 48 8b 6b 70 0f 85
RIP: batadv_iv_ogm_schedule_buff+0x9ca/0xeb0 net/batman-adv/bat_iv_ogm.c:1015 RSP: ffff88804feefc40
---[ end trace efc43a74d0d7393e ]---


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[Dmitry Vyukov]

#syz fix: batman-adv: Don't schedule OGM for disabled interface

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