KASAN: slab-out-of-bounds Read in icmpv6_xrlim_allow

From: syzbot
Date: Tue Jun 04 2019 - 01:05:05 EST

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Hello,

syzbot found the following crash on:

HEAD commit: 0462eaac Merge git://git.kernel.org/pub/scm/linux/kernel/g..
git tree: bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=12c82772a00000
kernel config: https://syzkaller.appspot.com/x/.config?x=b7b54c66298f8420
dashboard link: https://syzkaller.appspot.com/bug?extid=14536436e78408172703
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+14536436e78408172703@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: slab-out-of-bounds in icmpv6_xrlim_allow+0x409/0x440 net/ipv6/icmp.c:216
Read of size 8 at addr ffff8880973ed8bf by task swapper/1/0

CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.2.0-rc2+ #12
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188
__kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
kasan_report+0x12/0x20 mm/kasan/common.c:614
__asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
icmpv6_xrlim_allow+0x409/0x440 net/ipv6/icmp.c:216
icmp6_send+0x1107/0x1e50 net/ipv6/icmp.c:540
icmpv6_send+0xec/0x230 net/ipv6/ip6_icmp.c:43
ip6_link_failure+0x2b/0x530 net/ipv6/route.c:2367
dst_link_failure include/net/dst.h:416 [inline]
ndisc_error_report+0xce/0x1c0 net/ipv6/ndisc.c:712
neigh_invalidate+0x245/0x570 net/core/neighbour.c:1000
neigh_timer_handler+0xc33/0xf30 net/core/neighbour.c:1086
call_timer_fn+0x193/0x720 kernel/time/timer.c:1322
expire_timers kernel/time/timer.c:1366 [inline]
__run_timers kernel/time/timer.c:1685 [inline]
__run_timers kernel/time/timer.c:1653 [inline]
run_timer_softirq+0x66f/0x1740 kernel/time/timer.c:1698
__do_softirq+0x25c/0x94c kernel/softirq.c:293
invoke_softirq kernel/softirq.c:374 [inline]
irq_exit+0x180/0x1d0 kernel/softirq.c:414
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0x13b/0x550 arch/x86/kernel/apic/apic.c:1068
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:806
</IRQ>
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x54/0x90 kernel/locking/spinlock.c:199
Code: c0 00 74 b2 88 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 75 33 48 83 3d 85 ee 94 01 00 74 20 fb 66 0f 1f 44 00 00 <bf> 01 00 00 00 e8 52 f5 2f fa 65 8b 05 f3 77 e4 78 85 c0 74 06 41
RSP: 0018:ffff8880a98e7c88 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff1164e80 RBX: ffff8880a98d4340 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffff8880a98d4bbc
RBP: ffff8880a98e7c90 R08: ffff8880a98d4340 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880ae935080
R13: ffff888096ef0640 R14: 0000000000000000 R15: 0000000000000001
finish_lock_switch kernel/sched/core.c:2568 [inline]
finish_task_switch+0x146/0x730 kernel/sched/core.c:2668
context_switch kernel/sched/core.c:2821 [inline]
__schedule+0x7d3/0x1560 kernel/sched/core.c:3445
schedule_idle+0x58/0x80 kernel/sched/core.c:3537
do_idle+0x192/0x560 kernel/sched/idle.c:287
cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:354
start_secondary+0x34e/0x4c0 arch/x86/kernel/smpboot.c:265
secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243

Allocated by task 0:
save_stack+0x23/0x90 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_kmalloc mm/kasan/common.c:489 [inline]
__kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:497
slab_post_alloc_hook mm/slab.h:437 [inline]
slab_alloc mm/slab.c:3326 [inline]
kmem_cache_alloc+0x11a/0x6f0 mm/slab.c:3488
dst_alloc+0x10e/0x200 net/core/dst.c:93
ip6_dst_alloc+0x34/0xa0 net/ipv6/route.c:356
icmp6_dst_alloc+0x1a9/0x660 net/ipv6/route.c:2806
ndisc_send_skb+0xfc1/0x14a0 net/ipv6/ndisc.c:488
ndisc_send_rs+0x134/0x6d0 net/ipv6/ndisc.c:702
addrconf_rs_timer+0x30f/0x680 net/ipv6/addrconf.c:3880
call_timer_fn+0x193/0x720 kernel/time/timer.c:1322
expire_timers kernel/time/timer.c:1366 [inline]
__run_timers kernel/time/timer.c:1685 [inline]
__run_timers kernel/time/timer.c:1653 [inline]
run_timer_softirq+0x66f/0x1740 kernel/time/timer.c:1698
__do_softirq+0x25c/0x94c kernel/softirq.c:293

Freed by task 0:
save_stack+0x23/0x90 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/common.c:451
kasan_slab_free+0xe/0x10 mm/kasan/common.c:459
__cache_free mm/slab.c:3432 [inline]
kmem_cache_free+0x86/0x260 mm/slab.c:3698
dst_destroy+0x29e/0x3c0 net/core/dst.c:129
dst_destroy_rcu+0x16/0x19 net/core/dst.c:142
__rcu_reclaim kernel/rcu/rcu.h:222 [inline]
rcu_do_batch kernel/rcu/tree.c:2092 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2310 [inline]
rcu_core+0xba5/0x1500 kernel/rcu/tree.c:2291
__do_softirq+0x25c/0x94c kernel/softirq.c:293

The buggy address belongs to the object at ffff8880973ed780
which belongs to the cache ip6_dst_cache of size 224
The buggy address is located 95 bytes to the right of
224-byte region [ffff8880973ed780, ffff8880973ed860)
The buggy address belongs to the page:
page:ffffea00025cfb40 refcount:1 mapcount:0 mapping:ffff88809b0b8cc0 index:0xffff8880973ed000
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea00017a6288 ffffea00022d3f88 ffff88809b0b8cc0
raw: ffff8880973ed000 ffff8880973ed000 0000000100000002 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8880973ed780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880973ed800: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc

ffff8880973ed880: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00

^
ffff8880973ed900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8880973ed980: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

---
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