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BUG: KASAN: slab-out-of-bounds in setup_udp_tunnel_sock+0x43d/0x520 net/ipv4/udp_tunnel.c:78
Write of size 1 at addr ffff8880a3355e10 by task syz-executor.0/9867

CPU: 0 PID: 9867 Comm: syz-executor.0 Not tainted 5.5.0-rc7-syzkaller #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+0x197/0x210 lib/dump_stack.c:118
 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:639
 __asan_report_store1_noabort+0x17/0x20 mm/kasan/generic_report.c:137
 setup_udp_tunnel_sock+0x43d/0x520 net/ipv4/udp_tunnel.c:78
 gtp_encap_enable_socket+0x338/0x420 drivers/net/gtp.c:827
 gtp_encap_enable drivers/net/gtp.c:845 [inline]
 gtp_newlink+0x95/0xc60 drivers/net/gtp.c:666
 __rtnl_newlink+0x109e/0x1790 net/core/rtnetlink.c:3305
 rtnl_newlink+0x69/0xa0 net/core/rtnetlink.c:3363
 rtnetlink_rcv_msg+0x45e/0xaf0 net/core/rtnetlink.c:5424
 netlink_rcv_skb+0x177/0x450 net/netlink/af_netlink.c:2477
 rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:5442
 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
 netlink_unicast+0x58c/0x7d0 net/netlink/af_netlink.c:1328
 netlink_sendmsg+0x91c/0xea0 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:639 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:659
 ____sys_sendmsg+0x753/0x880 net/socket.c:2330
 ___sys_sendmsg+0x100/0x170 net/socket.c:2384
 __sys_sendmsg+0x105/0x1d0 net/socket.c:2417
 __compat_sys_sendmsg net/compat.c:642 [inline]
 __do_compat_sys_sendmsg net/compat.c:649 [inline]
 __se_compat_sys_sendmsg net/compat.c:646 [inline]
 __ia32_compat_sys_sendmsg+0x7a/0xb0 net/compat.c:646
 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
 do_fast_syscall_32+0x27b/0xe16 arch/x86/entry/common.c:408
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f5a9a9
Code: 00 00 00 89 d3 5b 5e 5f 5d c3 b8 80 96 98 00 eb c4 8b 04 24 c3 8b 1c 24 c3 8b 34 24 c3 8b 3c 24 c3 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:000000000848fb6c EFLAGS: 00000216 ORIG_RAX: 0000000000000172
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000020000100
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 9867:
 save_stack+0x23/0x90 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 __kasan_kmalloc mm/kasan/common.c:513 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:486
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:521
 slab_post_alloc_hook mm/slab.h:584 [inline]
 slab_alloc mm/slab.c:3320 [inline]
 kmem_cache_alloc+0x121/0x710 mm/slab.c:3484
 sk_prot_alloc+0x67/0x310 net/core/sock.c:1597
 sk_alloc+0x39/0xfd0 net/core/sock.c:1657
 inet_create net/ipv4/af_inet.c:321 [inline]
 inet_create+0x363/0xdf0 net/ipv4/af_inet.c:247
 __sock_create+0x3ce/0x730 net/socket.c:1420
 sock_create net/socket.c:1471 [inline]
 __sys_socket+0x103/0x220 net/socket.c:1513
 __do_sys_socket net/socket.c:1522 [inline]
 __se_sys_socket net/socket.c:1520 [inline]
 __ia32_sys_socket+0x73/0xb0 net/socket.c:1520
 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
 do_fast_syscall_32+0x27b/0xe16 arch/x86/entry/common.c:408
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8880a33558c0
 which belongs to the cache RAW of size 1360
The buggy address is located 0 bytes to the right of
 1360-byte region [ffff8880a33558c0, ffff8880a3355e10)
The buggy address belongs to the page:
page:ffffea00028cd500 refcount:1 mapcount:0 mapping:ffff8880a78d9540 index:0x0 compound_mapcount: 0
raw: 00fffe0000010200 ffffea00023ff708 ffff8880a52c7c48 ffff8880a78d9540
raw: 0000000000000000 ffff8880a33540c0 0000000100000005 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a3355d00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880a3355d80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8880a3355e00: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                         ^
 ffff8880a3355e80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a3355f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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