KASAN: slab-out-of-bounds Read in fib6_rule

Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KASAN: slab-out-of-bounds Read in fib6_rule_lookup (2) net				4	1789d	1852d	0/26	auto-closed as invalid on 2019/10/25 08:36
IPVS: ftp: loaded support on port[0] = 21
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BUG: KASAN: slab-out-of-bounds in fib6_rule_lookup+0x6fc/0x870 net/ipv6/fib6_rules.c:119
Read of size 2 at addr ffff888096883750 by task syz-executor0/22272

CPU: 0 PID: 22272 Comm: syz-executor0 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_load2_noabort+0x14/0x20 mm/kasan/report.c:431
 fib6_rule_lookup+0x6fc/0x870 net/ipv6/fib6_rules.c:119
 ip6_route_input_lookup+0xb7/0xd0 net/ipv6/route.c:1921
 ip6_route_input+0x79b/0xe00 net/ipv6/route.c:2056
 ip6_rcv_finish_core.isra.0+0x204/0x720 net/ipv6/ip6_input.c:63
 ip6_rcv_finish+0x109/0x330 net/ipv6/ip6_input.c:74
 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
 netif_receive_skb_internal+0x11e/0x690 net/core/dev.c:5186
 napi_frags_finish net/core/dev.c:5753 [inline]
 napi_gro_frags+0xd07/0xfe0 net/core/dev.c:5827
 tun_get_user+0x2ec2/0x4150 drivers/net/tun.c:1972
 tun_chr_write_iter+0xbd/0x160 drivers/net/tun.c:2017
 call_write_iter include/linux/fs.h:1857 [inline]
 do_iter_readv_writev+0x856/0xae0 fs/read_write.c:680
 do_iter_write fs/read_write.c:959 [inline]
 do_iter_write+0x184/0x600 fs/read_write.c:940
 vfs_writev+0x1ee/0x370 fs/read_write.c:1004
 do_writev+0x11a/0x300 fs/read_write.c:1039
 __do_sys_writev fs/read_write.c:1112 [inline]
 __se_sys_writev fs/read_write.c:1109 [inline]
 __x64_sys_writev+0x75/0xb0 fs/read_write.c:1109
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457d81
Code: 75 14 b8 14 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 a4 b8 fb ff c3 48 83 ec 08 e8 1a 2d 00 00 48 89 04 24 b8 14 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 63 2d 00 00 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007f75aeefaba0 EFLAGS: 00000293 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 000000000000004a RCX: 0000000000457d81
RDX: 0000000000000001 RSI: 00007f75aeefabf0 RDI: 00000000000000f0
RBP: 0000000020000080 R08: 00000000000000f0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 00007f75aeefb6d4
R13: 00000000004c636f R14: 00000000004db3f8 R15: 00000000ffffffff

Allocated by task 7704:
 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
 kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc+0x12e/0x700 mm/slab.c:3554
 anon_vma_alloc mm/rmap.c:82 [inline]
 anon_vma_fork+0x18e/0x880 mm/rmap.c:341
 dup_mmap kernel/fork.c:545 [inline]
 dup_mm kernel/fork.c:1323 [inline]
 copy_mm kernel/fork.c:1378 [inline]
 copy_process+0x3a53/0x8730 kernel/fork.c:1922
 _do_fork+0x1a9/0x1170 kernel/fork.c:2221
 __do_sys_clone kernel/fork.c:2328 [inline]
 __se_sys_clone kernel/fork.c:2322 [inline]
 __x64_sys_clone+0xbf/0x150 kernel/fork.c:2322
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff888096883698
 which belongs to the cache anon_vma of size 168
The buggy address is located 16 bytes to the right of
 168-byte region [ffff888096883698, ffff888096883740)
The buggy address belongs to the page:
page:ffffea00025a20c0 count:1 mapcount:0 mapping:ffff88821bc40340 index:0xffff888096883fef
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea000253c3c8 ffffea0002224608 ffff88821bc40340
raw: ffff888096883fef ffff888096883040 0000000100000011 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888096883600: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc
 ffff888096883680: fc fc fc 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888096883700: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
                                                 ^
 ffff888096883780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888096883800: 00 00 00 00 00 fc fc fc fc fc fc fc fc 00 00 00
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