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BUG: KASAN: use-after-free in ifname_compare_aligned include/linux/netfilter/x_tables.h:369 [inline]
BUG: KASAN: use-after-free in ip6_packet_match net/ipv6/netfilter/ip6_tables.c:89 [inline]
BUG: KASAN: use-after-free in ip6t_do_table+0x1545/0x1860 net/ipv6/netfilter/ip6_tables.c:333
Read of size 8 at addr ffff8801cc6bc000 by task syz-executor.0/31904

CPU: 1 PID: 31904 Comm: syz-executor.0 Not tainted 4.9.202+ #0
 ffff8801d83af058 ffffffff81b55d2b 0000000000000000 ffffea000731af00
 ffff8801cc6bc000 0000000000000008 ffffffff82784e15 ffff8801d83af090
 ffffffff8150c321 0000000000000000 ffff8801cc6bc000 ffff8801cc6bc000
Call Trace:
 [<00000000c8bdd8c7>] __dump_stack lib/dump_stack.c:15 [inline]
 [<00000000c8bdd8c7>] dump_stack+0xcb/0x130 lib/dump_stack.c:56
 [<000000003f3f0404>] print_address_description+0x6f/0x23a mm/kasan/report.c:256
 [<00000000adc16194>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<00000000adc16194>] kasan_report mm/kasan/report.c:413 [inline]
 [<00000000adc16194>] kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:397
 [<000000003f9e1faf>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:434
 [<00000000d33d7b32>] ifname_compare_aligned include/linux/netfilter/x_tables.h:369 [inline]
 [<00000000d33d7b32>] ip6_packet_match net/ipv6/netfilter/ip6_tables.c:89 [inline]
 [<00000000d33d7b32>] ip6t_do_table+0x1545/0x1860 net/ipv6/netfilter/ip6_tables.c:333
 [<00000000ac77b94e>] ip6t_mangle_out net/ipv6/netfilter/ip6table_mangle.c:63 [inline]
 [<00000000ac77b94e>] ip6table_mangle_hook+0x2dc/0x6d0 net/ipv6/netfilter/ip6table_mangle.c:85
 [<000000004e4aa202>] nf_iterate+0x12e/0x310 net/netfilter/core.c:324
 [<0000000089ab427b>] nf_hook_slow+0x114/0x1f0 net/netfilter/core.c:355
 [<00000000cb1aa6d3>] nf_hook_thresh include/linux/netfilter.h:191 [inline]
 [<00000000cb1aa6d3>] nf_hook include/linux/netfilter.h:203 [inline]
 [<00000000cb1aa6d3>] __ip6_local_out+0x498/0x630 net/ipv6/output_core.c:166
 [<00000000ded32cd3>] ip6_local_out+0x29/0x180 net/ipv6/output_core.c:176
 [<00000000cfdb9fd2>] ip6_send_skb+0xa2/0x340 net/ipv6/ip6_output.c:1753
 [<00000000e9b0e363>] udp_v6_send_skb+0x438/0xe90 net/ipv6/udp.c:974
 [<00000000109c9825>] udp_v6_push_pending_frames+0x245/0x360 net/ipv6/udp.c:1007
 [<000000000c5667e3>] udpv6_sendmsg+0x19b0/0x2430 net/ipv6/udp.c:1273
 [<0000000068730418>] inet_sendmsg+0x202/0x4d0 net/ipv4/af_inet.c:766
 [<00000000d8570105>] sock_sendmsg_nosec net/socket.c:649 [inline]
 [<00000000d8570105>] sock_sendmsg+0xbe/0x110 net/socket.c:659
 [<00000000db2bdc12>] ___sys_sendmsg+0x387/0x8b0 net/socket.c:1983
 [<0000000078db16af>] __sys_sendmmsg+0x164/0x3d0 net/socket.c:2073
 [<00000000da26d364>] SYSC_sendmmsg net/socket.c:2104 [inline]
 [<00000000da26d364>] SyS_sendmmsg+0x35/0x60 net/socket.c:2099
 [<0000000094928f85>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288
 [<00000000f46f34ed>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

The buggy address belongs to the page:
page:ffffea000731af00 count:0 mapcount:-127 mapping:          (null) index:0x0
flags: 0x4000000000000000()
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801cc6bbf00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8801cc6bbf80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8801cc6bc000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff8801cc6bc080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8801cc6bc100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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