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SubjectKASAN: use-after-free Read in ila_nf_input
From
Hello,

syzbot found the following crash on:

HEAD commit: b71acb0e3721 Merge branch 'linus' of git://git.kernel.org/..
git tree: bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15ab8b6f400000
kernel config: https://syzkaller.appspot.com/x/.config?x=b03c5892bb940c76
dashboard link: https://syzkaller.appspot.com/bug?extid=03a25358f4cba0bc4cb6
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+03a25358f4cba0bc4cb6@syzkaller.appspotmail.com

netlink: 'syz-executor2': attribute type 15 has an invalid length.
IPv6: RTM_NEWROUTE with no NLM_F_CREATE or NLM_F_REPLACE
==================================================================
BUG: KASAN: use-after-free in rht_key_hashfn include/linux/rhashtable.h:143
[inline]
BUG: KASAN: use-after-free in __rhashtable_lookup
include/linux/rhashtable.h:492 [inline]
BUG: KASAN: use-after-free in rhashtable_lookup
include/linux/rhashtable.h:534 [inline]
BUG: KASAN: use-after-free in rhashtable_lookup_fast
include/linux/rhashtable.h:560 [inline]
BUG: KASAN: use-after-free in ila_lookup_wildcards
net/ipv6/ila/ila_xlat.c:133 [inline]
BUG: KASAN: use-after-free in ila_xlat_addr net/ipv6/ila/ila_xlat.c:658
[inline]
BUG: KASAN: use-after-free in ila_nf_input+0xf52/0x1100
net/ipv6/ila/ila_xlat.c:191
Read of size 4 at addr ffff88808ba80ccc by task ksoftirqd/0/9

CPU: 0 PID: 9 Comm: ksoftirqd/0 Not tainted 4.20.0+ #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1db/0x2d0 lib/dump_stack.c:113
print_address_description.cold+0x7c/0x20d mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report mm/kasan/report.c:412 [inline]
kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:396
__asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
rht_key_hashfn include/linux/rhashtable.h:143 [inline]
__rhashtable_lookup include/linux/rhashtable.h:492 [inline]
rhashtable_lookup include/linux/rhashtable.h:534 [inline]
rhashtable_lookup_fast include/linux/rhashtable.h:560 [inline]
ila_lookup_wildcards net/ipv6/ila/ila_xlat.c:133 [inline]
ila_xlat_addr net/ipv6/ila/ila_xlat.c:658 [inline]
ila_nf_input+0xf52/0x1100 net/ipv6/ila/ila_xlat.c:191
nf_hook_entry_hookfn include/linux/netfilter.h:119 [inline]
nf_hook_slow+0xbf/0x1f0 net/netfilter/core.c:511
nf_hook include/linux/netfilter.h:244 [inline]
NF_HOOK include/linux/netfilter.h:287 [inline]
ipv6_rcv+0x3b9/0x650 net/ipv6/ip6_input.c:272
__netif_receive_skb_one_core+0x160/0x210 net/core/dev.c:4973
__netif_receive_skb+0x2c/0x1c0 net/core/dev.c:5083
process_backlog+0x206/0x750 net/core/dev.c:5923
napi_poll net/core/dev.c:6346 [inline]
net_rx_action+0x76d/0x1930 net/core/dev.c:6412
__do_softirq+0x30b/0xb11 kernel/softirq.c:292
run_ksoftirqd kernel/softirq.c:654 [inline]
run_ksoftirqd+0x8e/0x110 kernel/softirq.c:646
smpboot_thread_fn+0x6ab/0xa10 kernel/smpboot.c:164
kthread+0x357/0x430 kernel/kthread.c:246
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Allocated by task 7721:
save_stack+0x45/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
kasan_kmalloc mm/kasan/kasan.c:553 [inline]
kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:531
__do_kmalloc_node mm/slab.c:3684 [inline]
__kmalloc_node+0x51/0x80 mm/slab.c:3691
kmalloc_node include/linux/slab.h:589 [inline]
kvmalloc_node+0xbd/0x100 mm/util.c:416
kvmalloc include/linux/mm.h:577 [inline]
kvzalloc include/linux/mm.h:585 [inline]
bucket_table_alloc+0x9f/0x540 lib/rhashtable.c:176
rhashtable_init+0x525/0xa60 lib/rhashtable.c:1065
ila_xlat_init_net+0x26f/0x3d0 net/ipv6/ila/ila_xlat.c:623
ila_init_net+0x16/0x20 net/ipv6/ila/ila_main.c:63
ops_init+0x109/0x5d0 net/core/net_namespace.c:129
setup_net+0x326/0x8c0 net/core/net_namespace.c:314
copy_net_ns+0x2ae/0x4b0 net/core/net_namespace.c:437
create_new_namespaces+0x4ce/0x930 kernel/nsproxy.c:107
unshare_nsproxy_namespaces+0xc2/0x200 kernel/nsproxy.c:206
ksys_unshare+0x6d7/0xfb0 kernel/fork.c:2544
__do_sys_unshare kernel/fork.c:2612 [inline]
__se_sys_unshare kernel/fork.c:2610 [inline]
__x64_sys_unshare+0x31/0x40 kernel/fork.c:2610
do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 14703:
save_stack+0x45/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
__cache_free mm/slab.c:3498 [inline]
kfree+0xcf/0x230 mm/slab.c:3817
kvfree+0x61/0x70 mm/util.c:445
bucket_table_free+0xde/0x260 lib/rhashtable.c:108
rhashtable_free_and_destroy+0x155/0x8f0 lib/rhashtable.c:1163
ila_xlat_exit_net+0x22b/0x420 net/ipv6/ila/ila_xlat.c:632
ila_exit_net+0x16/0x20 net/ipv6/ila/ila_main.c:75
ops_exit_list.isra.0+0xb0/0x160 net/core/net_namespace.c:153
cleanup_net+0x51d/0xb10 net/core/net_namespace.c:551
process_one_work+0xd0c/0x1ce0 kernel/workqueue.c:2153
worker_thread+0x143/0x14a0 kernel/workqueue.c:2296
kthread+0x357/0x430 kernel/kthread.c:246
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff88808ba80cc0
which belongs to the cache kmalloc-32k of size 32768
The buggy address is located 12 bytes inside of
32768-byte region [ffff88808ba80cc0, ffff88808ba88cc0)
The buggy address belongs to the page:
page:ffffea00022ea000 count:1 mapcount:0 mapping:ffff88812c3f2380 index:0x0
compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea00022db008 ffffea000298d008 ffff88812c3f2380
raw: 0000000000000000 ffff88808ba80cc0 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88808ba80b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88808ba80c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff88808ba80c80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
^
ffff88808ba80d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88808ba80d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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