KASAN: use-after-free Read in nf_ct_deliver_cached_events

From: syzbot
Date: Tue Oct 22 2019 - 10:03:09 EST

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Hello,

syzbot found the following crash on:

HEAD commit: a6fcdcd9 Add linux-next specific files for 20191021
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=111b7fcf600000
kernel config: https://syzkaller.appspot.com/x/.config?x=32434321999f01e9
dashboard link: https://syzkaller.appspot.com/bug?extid=c7aabc9fe93e7f3637ba
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+c7aabc9fe93e7f3637ba@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: use-after-free in __nf_ct_ext_exist include/net/netfilter/nf_conntrack_extend.h:53 [inline]
BUG: KASAN: use-after-free in nf_ct_ext_exist include/net/netfilter/nf_conntrack_extend.h:58 [inline]
BUG: KASAN: use-after-free in __nf_ct_ext_find include/net/netfilter/nf_conntrack_extend.h:63 [inline]
BUG: KASAN: use-after-free in nf_ct_ecache_find include/net/netfilter/nf_conntrack_ecache.h:35 [inline]
BUG: KASAN: use-after-free in nf_ct_deliver_cached_events+0x5c3/0x6d0 net/netfilter/nf_conntrack_ecache.c:205
Read of size 1 at addr ffff88806bb2dc04 by task syz-executor.2/27585

CPU: 0 PID: 27585 Comm: syz-executor.2 Not tainted 5.4.0-rc4-next-20191021 #0
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+0x172/0x1f0 lib/dump_stack.c:113
print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
__kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
kasan_report+0x12/0x20 mm/kasan/common.c:634
__asan_report_load1_noabort+0x14/0x20 mm/kasan/generic_report.c:129
__nf_ct_ext_exist include/net/netfilter/nf_conntrack_extend.h:53 [inline]
nf_ct_ext_exist include/net/netfilter/nf_conntrack_extend.h:58 [inline]
__nf_ct_ext_find include/net/netfilter/nf_conntrack_extend.h:63 [inline]
nf_ct_ecache_find include/net/netfilter/nf_conntrack_ecache.h:35 [inline]
nf_ct_deliver_cached_events+0x5c3/0x6d0 net/netfilter/nf_conntrack_ecache.c:205
nf_conntrack_confirm include/net/netfilter/nf_conntrack_core.h:65 [inline]
nf_confirm+0x3d8/0x4d0 net/netfilter/nf_conntrack_proto.c:154
ipv4_confirm+0x14c/0x240 net/netfilter/nf_conntrack_proto.c:169
nf_hook_entry_hookfn include/linux/netfilter.h:135 [inline]
nf_hook_slow+0xbc/0x1e0 net/netfilter/core.c:512
nf_hook include/linux/netfilter.h:262 [inline]
NF_HOOK_COND include/linux/netfilter.h:295 [inline]
ip_output+0x40d/0x670 net/ipv4/ip_output.c:432
dst_output include/net/dst.h:436 [inline]
ip_local_out+0xbb/0x1b0 net/ipv4/ip_output.c:125
ip_send_skb+0x42/0xf0 net/ipv4/ip_output.c:1558
udp_send_skb.isra.0+0x6d5/0x11b0 net/ipv4/udp.c:891
udp_sendmsg+0x1e8f/0x2810 net/ipv4/udp.c:1178
inet_sendmsg+0x9e/0xe0 net/ipv4/af_inet.c:807
sock_sendmsg_nosec net/socket.c:638 [inline]
sock_sendmsg+0xd7/0x130 net/socket.c:658
kernel_sendmsg+0x44/0x50 net/socket.c:678
rxrpc_send_data_packet+0x10cb/0x36b0 net/rxrpc/output.c:416
rxrpc_queue_packet net/rxrpc/sendmsg.c:220 [inline]
rxrpc_send_data+0x1097/0x4130 net/rxrpc/sendmsg.c:427
rxrpc_do_sendmsg+0xb8e/0x1d5f net/rxrpc/sendmsg.c:736
rxrpc_sendmsg+0x4d6/0x5f0 net/rxrpc/af_rxrpc.c:585
sock_sendmsg_nosec net/socket.c:638 [inline]
sock_sendmsg+0xd7/0x130 net/socket.c:658
___sys_sendmsg+0x3e2/0x920 net/socket.c:2312
__sys_sendmmsg+0x1bf/0x4d0 net/socket.c:2414
__do_sys_sendmmsg net/socket.c:2443 [inline]
__se_sys_sendmmsg net/socket.c:2440 [inline]
__x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2440
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459a59
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f18acb64c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000459a59
RDX: 0000000000000001 RSI: 0000000020005c00 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f18acb656d4
R13: 00000000004c74b8 R14: 00000000004dd1a8 R15: 00000000ffffffff

Allocated by task 27585:
save_stack+0x23/0x90 mm/kasan/common.c:69
set_track mm/kasan/common.c:77 [inline]
__kasan_kmalloc mm/kasan/common.c:510 [inline]
__kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:483
kasan_krealloc+0x84/0xc0 mm/kasan/common.c:565
__do_krealloc mm/slab_common.c:1655 [inline]
krealloc+0xa6/0xd0 mm/slab_common.c:1710
nf_ct_ext_add+0x2c7/0x630 net/netfilter/nf_conntrack_extend.c:74
nf_ct_ecache_ext_add include/net/netfilter/nf_conntrack_ecache.h:55 [inline]
init_conntrack.isra.0+0x5ed/0x11a0 net/netfilter/nf_conntrack_core.c:1470
resolve_normal_ct net/netfilter/nf_conntrack_core.c:1547 [inline]
nf_conntrack_in+0xd94/0x1460 net/netfilter/nf_conntrack_core.c:1707
ipv4_conntrack_local+0x127/0x220 net/netfilter/nf_conntrack_proto.c:200
nf_hook_entry_hookfn include/linux/netfilter.h:135 [inline]
nf_hook_slow+0xbc/0x1e0 net/netfilter/core.c:512
nf_hook include/linux/netfilter.h:262 [inline]
__ip_local_out+0x403/0x870 net/ipv4/ip_output.c:114
ip_local_out+0x2d/0x1b0 net/ipv4/ip_output.c:123
ip_send_skb+0x42/0xf0 net/ipv4/ip_output.c:1558
udp_send_skb.isra.0+0x6d5/0x11b0 net/ipv4/udp.c:891
udp_sendmsg+0x1e8f/0x2810 net/ipv4/udp.c:1178
inet_sendmsg+0x9e/0xe0 net/ipv4/af_inet.c:807
sock_sendmsg_nosec net/socket.c:638 [inline]
sock_sendmsg+0xd7/0x130 net/socket.c:658
kernel_sendmsg+0x44/0x50 net/socket.c:678
rxrpc_send_data_packet+0x10cb/0x36b0 net/rxrpc/output.c:416
rxrpc_queue_packet net/rxrpc/sendmsg.c:220 [inline]
rxrpc_send_data+0x1097/0x4130 net/rxrpc/sendmsg.c:427
rxrpc_do_sendmsg+0xb8e/0x1d5f net/rxrpc/sendmsg.c:736
rxrpc_sendmsg+0x4d6/0x5f0 net/rxrpc/af_rxrpc.c:585
sock_sendmsg_nosec net/socket.c:638 [inline]
sock_sendmsg+0xd7/0x130 net/socket.c:658
___sys_sendmsg+0x3e2/0x920 net/socket.c:2312
__sys_sendmmsg+0x1bf/0x4d0 net/socket.c:2414
__do_sys_sendmmsg net/socket.c:2443 [inline]
__se_sys_sendmmsg net/socket.c:2440 [inline]
__x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2440
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 27585:
save_stack+0x23/0x90 mm/kasan/common.c:69
set_track mm/kasan/common.c:77 [inline]
kasan_set_free_info mm/kasan/common.c:332 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/common.c:471
kasan_slab_free+0xe/0x10 mm/kasan/common.c:480
__cache_free mm/slab.c:3426 [inline]
kfree+0x10a/0x2c0 mm/slab.c:3757
nf_ct_ext_destroy+0x2ab/0x2e0 net/netfilter/nf_conntrack_extend.c:38
nf_conntrack_free+0x8f/0xe0 net/netfilter/nf_conntrack_core.c:1418
destroy_conntrack+0x1a2/0x270 net/netfilter/nf_conntrack_core.c:626
nf_conntrack_destroy+0xed/0x230 net/netfilter/core.c:600
nf_conntrack_put include/linux/netfilter/nf_conntrack_common.h:34 [inline]
nf_conntrack_put include/linux/netfilter/nf_conntrack_common.h:31 [inline]
nf_ct_resolve_clash net/netfilter/nf_conntrack_core.c:915 [inline]
__nf_conntrack_confirm+0x21ca/0x2830 net/netfilter/nf_conntrack_core.c:1038
nf_conntrack_confirm include/net/netfilter/nf_conntrack_core.h:63 [inline]
nf_confirm+0x3e7/0x4d0 net/netfilter/nf_conntrack_proto.c:154
ipv4_confirm+0x14c/0x240 net/netfilter/nf_conntrack_proto.c:169
nf_hook_entry_hookfn include/linux/netfilter.h:135 [inline]
nf_hook_slow+0xbc/0x1e0 net/netfilter/core.c:512
nf_hook include/linux/netfilter.h:262 [inline]
NF_HOOK_COND include/linux/netfilter.h:295 [inline]
ip_output+0x40d/0x670 net/ipv4/ip_output.c:432
dst_output include/net/dst.h:436 [inline]
ip_local_out+0xbb/0x1b0 net/ipv4/ip_output.c:125
ip_send_skb+0x42/0xf0 net/ipv4/ip_output.c:1558
udp_send_skb.isra.0+0x6d5/0x11b0 net/ipv4/udp.c:891
udp_sendmsg+0x1e8f/0x2810 net/ipv4/udp.c:1178
inet_sendmsg+0x9e/0xe0 net/ipv4/af_inet.c:807
sock_sendmsg_nosec net/socket.c:638 [inline]
sock_sendmsg+0xd7/0x130 net/socket.c:658
kernel_sendmsg+0x44/0x50 net/socket.c:678
rxrpc_send_data_packet+0x10cb/0x36b0 net/rxrpc/output.c:416
rxrpc_queue_packet net/rxrpc/sendmsg.c:220 [inline]
rxrpc_send_data+0x1097/0x4130 net/rxrpc/sendmsg.c:427
rxrpc_do_sendmsg+0xb8e/0x1d5f net/rxrpc/sendmsg.c:736
rxrpc_sendmsg+0x4d6/0x5f0 net/rxrpc/af_rxrpc.c:585
sock_sendmsg_nosec net/socket.c:638 [inline]
sock_sendmsg+0xd7/0x130 net/socket.c:658
___sys_sendmsg+0x3e2/0x920 net/socket.c:2312
__sys_sendmmsg+0x1bf/0x4d0 net/socket.c:2414
__do_sys_sendmmsg net/socket.c:2443 [inline]
__se_sys_sendmmsg net/socket.c:2440 [inline]
__x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2440
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88806bb2dc00
which belongs to the cache kmalloc-128 of size 128
The buggy address is located 4 bytes inside of
128-byte region [ffff88806bb2dc00, ffff88806bb2dc80)
The buggy address belongs to the page:
page:ffffea0001aecb40 refcount:1 mapcount:0 mapping:ffff8880aa400700 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea0002506788 ffffea00026a2c48 ffff8880aa400700
raw: 0000000000000000 ffff88806bb2d000 0000000100000010 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88806bb2db00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88806bb2db80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

ffff88806bb2dc00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

^
ffff88806bb2dc80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88806bb2dd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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