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BUG: KMSAN: uninit-value in gue_err+0x514/0xfa0 net/ipv4/fou.c:1032
CPU: 1 PID: 11460 Comm: syz-executor.4 Not tainted 5.0.0+ #17
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+0x173/0x1d0 lib/dump_stack.c:113
 kmsan_report+0x131/0x2a0 mm/kmsan/kmsan.c:624
 __msan_warning+0x7a/0xf0 mm/kmsan/kmsan_instr.c:310
 gue_err+0x514/0xfa0 net/ipv4/fou.c:1032
 __udp4_lib_err_encap_no_sk net/ipv4/udp.c:571 [inline]
 __udp4_lib_err_encap net/ipv4/udp.c:626 [inline]
 __udp4_lib_err+0x12e6/0x1d40 net/ipv4/udp.c:665
 udp_err+0x74/0x90 net/ipv4/udp.c:737
 icmp_socket_deliver net/ipv4/icmp.c:767 [inline]
 icmp_unreach+0xb65/0x1070 net/ipv4/icmp.c:884
 icmp_rcv+0x11a1/0x1950 net/ipv4/icmp.c:1066
 ip_protocol_deliver_rcu+0x584/0xbb0 net/ipv4/ip_input.c:208
 ip_local_deliver_finish net/ipv4/ip_input.c:234 [inline]
 NF_HOOK include/linux/netfilter.h:289 [inline]
 ip_local_deliver+0x624/0x7b0 net/ipv4/ip_input.c:255
 dst_input include/net/dst.h:450 [inline]
 ip_rcv_finish net/ipv4/ip_input.c:414 [inline]
 NF_HOOK include/linux/netfilter.h:289 [inline]
 ip_rcv+0x6bd/0x740 net/ipv4/ip_input.c:524
 __netif_receive_skb_one_core net/core/dev.c:4973 [inline]
 __netif_receive_skb net/core/dev.c:5083 [inline]
 process_backlog+0x756/0x10e0 net/core/dev.c:5923
 napi_poll net/core/dev.c:6346 [inline]
 net_rx_action+0x78b/0x1a60 net/core/dev.c:6412
 __do_softirq+0x53f/0x93a kernel/softirq.c:293
 do_softirq_own_stack+0x49/0x80 arch/x86/entry/entry_64.S:1039
 </IRQ>
 do_softirq kernel/softirq.c:338 [inline]
 __local_bh_enable_ip+0x16f/0x1a0 kernel/softirq.c:190
 local_bh_enable+0x36/0x40 include/linux/bottom_half.h:32
 rcu_read_unlock_bh include/linux/rcupdate.h:696 [inline]
 ip_finish_output2+0x1627/0x1820 net/ipv4/ip_output.c:231
 ip_finish_output+0xd2b/0xfd0 net/ipv4/ip_output.c:317
 NF_HOOK_COND include/linux/netfilter.h:278 [inline]
 ip_output+0x53f/0x610 net/ipv4/ip_output.c:405
 dst_output include/net/dst.h:444 [inline]
 ip_local_out net/ipv4/ip_output.c:124 [inline]
 ip_send_skb+0x179/0x360 net/ipv4/ip_output.c:1465
 udp_send_skb+0xf25/0x18b0 net/ipv4/udp.c:901
 udp_sendmsg+0x3aa4/0x40f0 net/ipv4/udp.c:1188
 udpv6_sendmsg+0x13c1/0x4500 net/ipv6/udp.c:1289
 inet_sendmsg+0x54a/0x720 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg net/socket.c:632 [inline]
 ___sys_sendmsg+0xdb9/0x11b0 net/socket.c:2115
 __sys_sendmmsg+0x580/0xad0 net/socket.c:2210
 __do_sys_sendmmsg net/socket.c:2239 [inline]
 __se_sys_sendmmsg+0xbd/0xe0 net/socket.c:2236
 __x64_sys_sendmmsg+0x56/0x70 net/socket.c:2236
 do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x458209
Code: ad b8 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 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fb1655edc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000458209
RDX: 04000000000001b9 RSI: 00000000200092c0 RDI: 0000000000000003
RBP: 000000000073bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb1655ee6d4
R13: 00000000004c513e R14: 00000000004d8ec0 R15: 00000000ffffffff

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline]
 kmsan_internal_poison_shadow+0x92/0x150 mm/kmsan/kmsan.c:159
 kmsan_kmalloc+0xa6/0x130 mm/kmsan/kmsan_hooks.c:173
 kmsan_slab_alloc+0xe/0x10 mm/kmsan/kmsan_hooks.c:182
 slab_post_alloc_hook mm/slab.h:445 [inline]
 slab_alloc_node mm/slub.c:2773 [inline]
 __kmalloc_node_track_caller+0xe9e/0xff0 mm/slub.c:4398
 __kmalloc_reserve net/core/skbuff.c:140 [inline]
 pskb_expand_head+0x220/0x18f0 net/core/skbuff.c:1469
 __pskb_pull_tail+0x1a7/0x2230 net/core/skbuff.c:1900
 skb_make_writable+0x3e4/0x4c0 net/netfilter/core.c:556
 nf_nat_icmp_reply_translation+0x212/0x9a0 net/ipv4/netfilter/nf_nat_l3proto_ipv4.c:178
 nf_nat_ipv4_fn net/ipv4/netfilter/nf_nat_l3proto_ipv4.c:239 [inline]
 nf_nat_ipv4_in+0x2ad/0x590 net/ipv4/netfilter/nf_nat_l3proto_ipv4.c:257
 nf_hook_entry_hookfn include/linux/netfilter.h:119 [inline]
 nf_hook_slow+0x176/0x3d0 net/netfilter/core.c:511
 nf_hook include/linux/netfilter.h:244 [inline]
 NF_HOOK include/linux/netfilter.h:287 [inline]
 ip_rcv+0x24e/0x740 net/ipv4/ip_input.c:524
 __netif_receive_skb_one_core net/core/dev.c:4973 [inline]
 __netif_receive_skb net/core/dev.c:5083 [inline]
 process_backlog+0x756/0x10e0 net/core/dev.c:5923
 napi_poll net/core/dev.c:6346 [inline]
 net_rx_action+0x78b/0x1a60 net/core/dev.c:6412
 __do_softirq+0x53f/0x93a kernel/softirq.c:293
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