syzbot


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

Status: fixed on 2019/03/06 07:43
Subsystems: net
[Documentation on labels]
Reported-by: syzbot+485623f77eab9345799d@syzkaller.appspotmail.com
Fix commit: 12750abad517 xfrm: policy: fix infinite loop when merging src-nodes
First crash: 2185d, last: 2162d
Discussions (1)
Title Replies (including bot) Last reply
KASAN: slab-out-of-bounds Read in xfrm_policy_lookup_bytype 0 (1) 2018/12/20 12:10

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in __xfrm_policy_eval_candidates net/xfrm/xfrm_policy.c:2019 [inline]
BUG: KASAN: slab-out-of-bounds in xfrm_policy_eval_candidates net/xfrm/xfrm_policy.c:2053 [inline]
BUG: KASAN: slab-out-of-bounds in xfrm_policy_lookup_bytype+0xd27/0xdb0 net/xfrm/xfrm_policy.c:2113
Read of size 4 at addr ffff888093fc09f4 by task syz-executor4/10838

CPU: 1 PID: 10838 Comm: syz-executor4 Not tainted 4.20.0+ #16
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+0x1db/0x2d0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187
 kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/generic_report.c:134
 __xfrm_policy_eval_candidates net/xfrm/xfrm_policy.c:2019 [inline]
 xfrm_policy_eval_candidates net/xfrm/xfrm_policy.c:2053 [inline]
 xfrm_policy_lookup_bytype+0xd27/0xdb0 net/xfrm/xfrm_policy.c:2113
 xfrm_policy_lookup+0x7e/0x90 net/xfrm/xfrm_policy.c:2145
 __xfrm_policy_check+0x1426/0x2b00 net/xfrm/xfrm_policy.c:3354
 __xfrm_policy_check2 include/net/xfrm.h:1166 [inline]
 xfrm_policy_check include/net/xfrm.h:1175 [inline]
 xfrm6_policy_check include/net/xfrm.h:1185 [inline]
 udpv6_queue_rcv_one_skb+0x532/0x1750 net/ipv6/udp.c:615
 udpv6_queue_rcv_skb+0x128/0x730 net/ipv6/udp.c:699
 __udp6_lib_mcast_deliver net/ipv6/udp.c:812 [inline]
 __udp6_lib_rcv+0x1e8d/0x30d0 net/ipv6/udp.c:916
 udpv6_rcv+0x22/0x30 net/ipv6/udp.c:1026
 ip6_protocol_deliver_rcu+0x3aa/0x1940 net/ipv6/ip6_input.c:394
 ip6_input_finish+0x84/0x170 net/ipv6/ip6_input.c:434
 NF_HOOK include/linux/netfilter.h:289 [inline]
 NF_HOOK include/linux/netfilter.h:283 [inline]
 ip6_input+0xf9/0x600 net/ipv6/ip6_input.c:443
 ip6_mc_input+0x4f9/0x10d0 net/ipv6/ip6_input.c:537
 dst_input include/net/dst.h:450 [inline]
 ip6_rcv_finish+0x177/0x330 net/ipv6/ip6_input.c:76
 NF_HOOK include/linux/netfilter.h:289 [inline]
 NF_HOOK include/linux/netfilter.h:283 [inline]
 ipv6_rcv+0x113/0x650 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
 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1027
 </IRQ>
 do_softirq.part.0+0x11a/0x170 kernel/softirq.c:337
 do_softirq+0x18/0x20 kernel/softirq.c:325
 netif_rx_ni+0x4fd/0x860 net/core/dev.c:4569
 dev_loopback_xmit+0x29b/0x8c0 net/core/dev.c:3576
 NF_HOOK include/linux/netfilter.h:289 [inline]
 NF_HOOK include/linux/netfilter.h:283 [inline]
 ip6_finish_output2+0x1a03/0x28e0 net/ipv6/ip6_output.c:84
 ip6_finish_output+0x577/0xc30 net/ipv6/ip6_output.c:154
 NF_HOOK_COND include/linux/netfilter.h:278 [inline]
 ip6_output+0x23c/0xa00 net/ipv6/ip6_output.c:171
 dst_output include/net/dst.h:444 [inline]
 ip6_local_out+0xc4/0x1b0 net/ipv6/output_core.c:176
 ip6_send_skb+0xbb/0x350 net/ipv6/ip6_output.c:1727
 udp_v6_send_skb.isra.0+0x834/0x14b0 net/ipv6/udp.c:1169
 udpv6_sendmsg+0x2ba8/0x3570 net/ipv6/udp.c:1466
 inet_sendmsg+0x1af/0x740 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg+0xdd/0x130 net/socket.c:631
 __sys_sendto+0x387/0x5f0 net/socket.c:1788
 __do_sys_sendto net/socket.c:1800 [inline]
 __se_sys_sendto net/socket.c:1796 [inline]
 __x64_sys_sendto+0xe1/0x1a0 net/socket.c:1796
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457ec9
Code: 6d 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 3b b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fe2cb9cac78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 0000000000457ec9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 000000000073bf00 R08: 0000000020000300 R09: 000000000000001c
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe2cb9cb6d4
R13: 00000000004c53f5 R14: 00000000004d8ef0 R15: 00000000ffffffff

Allocated by task 7722:
 save_stack+0x45/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 kasan_kmalloc mm/kasan/common.c:482 [inline]
 kasan_kmalloc+0xcf/0xe0 mm/kasan/common.c:455
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:397
 kmem_cache_alloc+0x12d/0x710 mm/slab.c:3541
 getname_flags fs/namei.c:140 [inline]
 getname_flags+0xd6/0x5b0 fs/namei.c:129
 getname fs/namei.c:211 [inline]
 user_path_mountpoint_at+0x29/0x50 fs/namei.c:2747
 ksys_umount+0x198/0x1340 fs/namespace.c:1645
 __do_sys_umount fs/namespace.c:1671 [inline]
 __se_sys_umount fs/namespace.c:1669 [inline]
 __x64_sys_umount+0x54/0x80 fs/namespace.c:1669
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 7722:
 save_stack+0x45/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:444
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:452
 __cache_free mm/slab.c:3485 [inline]
 kmem_cache_free+0x86/0x260 mm/slab.c:3747
 putname+0xef/0x130 fs/namei.c:261
 filename_mountpoint+0x337/0x490 fs/namei.c:2725
 user_path_mountpoint_at+0x3a/0x50 fs/namei.c:2747
 ksys_umount+0x198/0x1340 fs/namespace.c:1645
 __do_sys_umount fs/namespace.c:1671 [inline]
 __se_sys_umount fs/namespace.c:1669 [inline]
 __x64_sys_umount+0x54/0x80 fs/namespace.c:1669
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888093fc0c80
 which belongs to the cache names_cache of size 4096
The buggy address is located 652 bytes to the left of
 4096-byte region [ffff888093fc0c80, ffff888093fc1c80)
The buggy address belongs to the page:
page:ffffea00024ff000 count:1 mapcount:0 mapping:ffff88821bc49080 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea00028cfa88 ffffea00027e9608 ffff88821bc49080
raw: 0000000000000000 ffff888093fc0c80 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888093fc0880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888093fc0900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888093fc0980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                                             ^
 ffff888093fc0a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888093fc0a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/01/11 11:48 net-old b19bce0335e2 80dde172 .config console log report ci-upstream-net-this-kasan-gce
2019/01/03 20:30 net-old c5ee066333eb 66fcd29b .config console log report ci-upstream-net-this-kasan-gce
2019/01/03 09:46 net-old d63967e475ae 06a2b89f .config console log report ci-upstream-net-this-kasan-gce
2019/01/01 15:59 net-old 756af9c64232 3d85f48c .config console log report ci-upstream-net-this-kasan-gce
2018/12/24 11:12 net-next-old ce28bb445388 be79df56 .config console log report ci-upstream-net-kasan-gce
2018/12/19 22:37 net-next-old 33f18c96afdf fe2dc057 .config console log report ci-upstream-net-kasan-gce
* Struck through repros no longer work on HEAD.