general protection fault in ip6_dst_destroy

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: b98aebd2 Linux 4.14.150
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=102c69df600000
kernel config: https://syzkaller.appspot.com/x/.config?x=c52c93b368dac5a7
dashboard link: https://syzkaller.appspot.com/bug?extid=5766161b0f1a98a4e4c1
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16d251c0e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1283af50e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+576616...@syzkaller.appspotmail.com

audit: type=1400 audit(1572039084.635:36): avc: denied { map } for
pid=6894 comm="syz-executor396" path="/root/syz-executor396406444"
dev="sda1" ino=16484 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
IPVS: ftp: loaded support on port[0] = 21
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: 1 PID: 0 Comm: swapper/1 Not tainted 4.14.150 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
task: ffff8880a9d1c340 task.stack: ffff8880a9d28000
RIP: 0010:__lock_acquire+0x1ba/0x4620 kernel/locking/lockdep.c:3365
RSP: 0018:ffff8880aef07b30 EFLAGS: 00010006
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffff8880aef07cd8 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: ffff8880a9d1c340 R12: 0000000000000018
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880aef00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000049f450 CR3: 000000008bfa4000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x33/0x50 kernel/locking/spinlock.c:176
spin_lock_bh include/linux/spinlock.h:322 [inline]
rt6_uncached_list_del net/ipv6/route.c:143 [inline]
ip6_dst_destroy+0x104/0x3b0 net/ipv6/route.c:400
dst_destroy+0xc4/0x330 net/core/dst.c:129
dst_destroy_rcu+0x16/0x20 net/core/dst.c:151
__rcu_reclaim kernel/rcu/rcu.h:195 [inline]
rcu_do_batch kernel/rcu/tree.c:2699 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2962 [inline]
__rcu_process_callbacks kernel/rcu/tree.c:2929 [inline]
rcu_process_callbacks+0x7b8/0x12b0 kernel/rcu/tree.c:2946
__do_softirq+0x244/0x9a0 kernel/softirq.c:288
invoke_softirq kernel/softirq.c:368 [inline]
irq_exit+0x160/0x1b0 kernel/softirq.c:409
exiting_irq arch/x86/include/asm/apic.h:648 [inline]
smp_apic_timer_interrupt+0x146/0x5e0 arch/x86/kernel/apic/apic.c:1102
apic_timer_interrupt+0x96/0xa0 arch/x86/entry/entry_64.S:792
</IRQ>
RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61
RSP: 0018:ffff8880a9d2fe70 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff10
RAX: 1ffffffff0ee2a84 RBX: ffff8880a9d1c340 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000001 RDI: ffff8880a9d1cbbc
RBP: ffff8880a9d2fe98 R08: 1ffffffff104ab01 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff87715410
R13: 0000000000000000 R14: 0000000000000000 R15: ffff8880a9d1c340
arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:557
default_idle_call+0x36/0x90 kernel/sched/idle.c:98
cpuidle_idle_call kernel/sched/idle.c:156 [inline]
do_idle+0x262/0x3d0 kernel/sched/idle.c:246
cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:351
start_secondary+0x346/0x4b0 arch/x86/kernel/smpboot.c:272
secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240
Code: 00 c7 40 18 00 00 00 00 48 8d 65 d8 44 89 e0 5b 41 5c 41 5d 41 5e 41
5f 5d c3 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00
0f 85 ac 2e 00 00 49 81 3c 24 a0 91 5d 88 0f 84 43
RIP: __lock_acquire+0x1ba/0x4620 kernel/locking/lockdep.c:3365 RSP:
ffff8880aef07b30
---[ end trace 7267a310ef0399eb ]---


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