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KASAN: slab-out-of-bounds Write in fib6_purge_rt

Status: fixed on 2019/06/18 17:49
Subsystems: net
[Documentation on labels]
Fix commit: 61fb0d016807 ipv6: prevent possible fib6 leaks
First crash: 1859d, last: 1823d

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in fib6_drop_pcpu_from net/ipv6/ip6_fib.c:921 [inline]
BUG: KASAN: slab-out-of-bounds in fib6_purge_rt+0x1b3/0x5e0 net/ipv6/ip6_fib.c:933
Write of size 8 at addr ffff88809848f4e4 by task syz-executor.2/2024

CPU: 0 PID: 2024 Comm: syz-executor.2 Not tainted 5.2.0-rc3+ #56
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.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
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x123/0x190 mm/kasan/generic.c:191
 kasan_check_write+0x14/0x20 mm/kasan/common.c:100
 fib6_drop_pcpu_from net/ipv6/ip6_fib.c:921 [inline]
 fib6_purge_rt+0x1b3/0x5e0 net/ipv6/ip6_fib.c:933
 fib6_del_route net/ipv6/ip6_fib.c:1808 [inline]
 fib6_del+0xac2/0x10a0 net/ipv6/ip6_fib.c:1839
 fib6_clean_node+0x3a5/0x590 net/ipv6/ip6_fib.c:2001
 fib6_walk_continue+0x4a9/0x8e0 net/ipv6/ip6_fib.c:1923
 fib6_walk+0x9d/0x100 net/ipv6/ip6_fib.c:1971
 fib6_clean_tree+0xe0/0x120 net/ipv6/ip6_fib.c:2050
 __fib6_clean_all+0x118/0x2a0 net/ipv6/ip6_fib.c:2066
 fib6_clean_all+0x2b/0x40 net/ipv6/ip6_fib.c:2077
 rt6_sync_down_dev+0x134/0x150 net/ipv6/route.c:4165
 rt6_disable_ip+0x27/0x5f0 net/ipv6/route.c:4170
 addrconf_ifdown+0xa2/0x1220 net/ipv6/addrconf.c:3705
 addrconf_notify+0x5db/0x2270 net/ipv6/addrconf.c:3630
 notifier_call_chain+0xc2/0x230 kernel/notifier.c:95
 __raw_notifier_call_chain kernel/notifier.c:396 [inline]
 raw_notifier_call_chain+0x2e/0x40 kernel/notifier.c:403
 call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1749
 call_netdevice_notifiers_extack net/core/dev.c:1761 [inline]
 call_netdevice_notifiers net/core/dev.c:1775 [inline]
 __dev_notify_flags+0x1e9/0x2c0 net/core/dev.c:7618
 dev_change_flags+0x10d/0x170 net/core/dev.c:7654
 devinet_ioctl+0x138a/0x1c50 net/ipv4/devinet.c:1100
 inet_ioctl+0x1f4/0x340 net/ipv4/af_inet.c:948
 sock_do_ioctl+0xd8/0x2f0 net/socket.c:1043
 sock_ioctl+0x3ed/0x780 net/socket.c:1194
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:696
 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4592c9
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:00007fefc208bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004592c9
RDX: 0000000020000040 RSI: 0000000000008914 RDI: 0000000000000007
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fefc208c6d4
R13: 00000000004c4f17 R14: 00000000004d8f60 R15: 00000000ffffffff

Allocated by task 28077:
 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:352
 ip6_rt_pcpu_alloc net/ipv6/route.c:1253 [inline]
 rt6_make_pcpu_route net/ipv6/route.c:1283 [inline]
 ip6_pol_route+0x659/0x1050 net/ipv6/route.c:1955
 ip6_pol_route_output+0x54/0x70 net/ipv6/route.c:2128
 fib6_rule_lookup+0x133/0x5a0 net/ipv6/fib6_rules.c:116
 ip6_route_output_flags+0x2c4/0x350 net/ipv6/route.c:2157
 ip6_route_output include/net/ip6_route.h:89 [inline]
 ip6_dst_lookup_tail+0xd10/0x1b30 net/ipv6/ip6_output.c:962
 ip6_dst_lookup_flow+0xa8/0x220 net/ipv6/ip6_output.c:1090
 sctp_v6_get_dst+0x785/0x1ce0 net/sctp/ipv6.c:278
 sctp_transport_route+0x12d/0x360 net/sctp/transport.c:297
 sctp_assoc_add_peer+0x53e/0xfc0 net/sctp/associola.c:663
 sctp_process_param net/sctp/sm_make_chunk.c:2522 [inline]
 sctp_process_init+0x273c/0x2e10 net/sctp/sm_make_chunk.c:2343
 sctp_sf_do_unexpected_init net/sctp/sm_statefuns.c:1541 [inline]
 sctp_sf_do_unexpected_init.isra.0+0x7cd/0x1350 net/sctp/sm_statefuns.c:1441
 sctp_sf_do_5_2_1_siminit+0x35/0x40 net/sctp/sm_statefuns.c:1670
 sctp_do_sm+0x121/0x5190 net/sctp/sm_sideeffect.c:1152
 sctp_assoc_bh_rcv+0x343/0x660 net/sctp/associola.c:1059
 sctp_inq_push+0x1e4/0x280 net/sctp/inqueue.c:80
 sctp_backlog_rcv+0x196/0xbe0 net/sctp/input.c:339
 sk_backlog_rcv include/net/sock.h:945 [inline]
 __release_sock+0x129/0x390 net/core/sock.c:2417
 release_sock+0x59/0x1c0 net/core/sock.c:2933
 sctp_wait_for_connect+0x316/0x540 net/sctp/socket.c:9039
 __sctp_connect+0xab2/0xcd0 net/sctp/socket.c:1226
 sctp_connect net/sctp/socket.c:4846 [inline]
 sctp_inet_connect+0x29c/0x340 net/sctp/socket.c:4862
 __sys_connect+0x264/0x330 net/socket.c:1834
 __do_sys_connect net/socket.c:1845 [inline]
 __se_sys_connect net/socket.c:1842 [inline]
 __x64_sys_connect+0x73/0xb0 net/socket.c:1842
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 19879:
 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 ffff88809848f400
 which belongs to the cache ip6_dst_cache of size 224
The buggy address is located 4 bytes to the right of
 224-byte region [ffff88809848f400, ffff88809848f4e0)
The buggy address belongs to the page:
page:ffffea00026123c0 refcount:1 mapcount:0 mapping:ffff88809b211d80 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea000225f588 ffffea0002485e48 ffff88809b211d80
raw: 0000000000000000 ffff88809848f040 000000010000000c 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809848f380: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809848f400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88809848f480: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
                                                       ^
 ffff88809848f500: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
 ffff88809848f580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/06/18 03:05 net-old 6be8e297f9bc 442206d7 .config console log report ci-upstream-net-this-kasan-gce
2019/06/06 20:26 net-old 4970b42d5c36 698773cb .config console log report ci-upstream-net-this-kasan-gce
2019/05/28 19:06 net-old d484e06e25eb 6bd61501 .config console log report ci-upstream-net-this-kasan-gce
2019/05/27 02:51 net-old 334031219a84 85c57315 .config console log report ci-upstream-net-this-kasan-gce
2019/05/25 23:06 net-old 4097e9d250fb 85c57315 .config console log report ci-upstream-net-this-kasan-gce
2019/05/13 11:45 net-old 69dda13fdaff 16ab1e89 .config console log report ci-upstream-net-this-kasan-gce
* Struck through repros no longer work on HEAD.