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BUG: KMSAN: uninit-value in inet_gro_receive+0x166c/0x1980 net/ipv4/af_inet.c:1418
CPU: 1 PID: 15 Comm: ksoftirqd/1 Not tainted 4.17.0-rc5+ #103
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+0x185/0x1d0 lib/dump_stack.c:113
 kmsan_report+0x149/0x260 mm/kmsan/kmsan.c:1084
 __msan_warning_32+0x6e/0xc0 mm/kmsan/kmsan_instr.c:686
 inet_gro_receive+0x166c/0x1980 net/ipv4/af_inet.c:1418
 dev_gro_receive+0x20a7/0x3230 net/core/dev.c:4989
 napi_gro_receive+0x61f/0xb50 net/core/dev.c:5124
 gro_cell_poll+0x28e/0x410 net/core/gro_cells.c:46
device syz_tun left promiscuous mode
 napi_poll net/core/dev.c:5735 [inline]
 net_rx_action+0x7c1/0x1a70 net/core/dev.c:5801
 __do_softirq+0x56d/0x93d kernel/softirq.c:285
 run_ksoftirqd+0x1f/0x40 kernel/softirq.c:646
 smpboot_thread_fn+0x488/0x970 kernel/smpboot.c:164
 kthread+0x4e3/0x6d0 kernel/kthread.c:241
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:412

Uninit was stored to memory at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:279 [inline]
 kmsan_save_stack mm/kmsan/kmsan.c:294 [inline]
 kmsan_internal_chain_origin+0x12b/0x210 mm/kmsan/kmsan.c:685
 kmsan_memcpy_origins+0x11d/0x170 mm/kmsan/kmsan.c:527
 __msan_memcpy+0x109/0x160 mm/kmsan/kmsan_instr.c:478
 pskb_expand_head+0x3a6/0x1a70 net/core/skbuff.c:1470
 __pskb_pull_tail+0x1d7/0x2300 net/core/skbuff.c:1881
 __skb_linearize include/linux/skbuff.h:3029 [inline]
 skb_checksum_help+0x250/0xb40 net/core/dev.c:2686
 skb_csum_hwoffload_help net/core/dev.c:3103 [inline]
 validate_xmit_skb+0x10fb/0x1320 net/core/dev.c:3142
 __dev_queue_xmit+0x216a/0x3510 net/core/dev.c:3576
 dev_queue_xmit+0x4b/0x60 net/core/dev.c:3617
 neigh_hh_output include/net/neighbour.h:472 [inline]
 neigh_output include/net/neighbour.h:480 [inline]
 ip_finish_output2+0x12bf/0x1490 net/ipv4/ip_output.c:229
 ip_finish_output+0xcaf/0xff0 net/ipv4/ip_output.c:317
 NF_HOOK_COND include/linux/netfilter.h:277 [inline]
 ip_output+0x505/0x5d0 net/ipv4/ip_output.c:405
 dst_output include/net/dst.h:444 [inline]
 ip_local_out+0x15e/0x1d0 net/ipv4/ip_output.c:124
 iptunnel_xmit+0x84b/0xda0 net/ipv4/ip_tunnel_core.c:91
 ip_tunnel_xmit+0x30d2/0x37b0 net/ipv4/ip_tunnel.c:778
 ipip_tunnel_xmit+0x32b/0x4c0 net/ipv4/ipip.c:308
 __netdev_start_xmit include/linux/netdevice.h:4087 [inline]
 netdev_start_xmit include/linux/netdevice.h:4096 [inline]
 xmit_one net/core/dev.c:3053 [inline]
 dev_hard_start_xmit+0x5f1/0xc70 net/core/dev.c:3069
 __dev_queue_xmit+0x2311/0x3510 net/core/dev.c:3584
 dev_queue_xmit+0x4b/0x60 net/core/dev.c:3617
 neigh_direct_output+0x42/0x50 net/core/neighbour.c:1398
 neigh_output include/net/neighbour.h:482 [inline]
 ip_finish_output2+0x1362/0x1490 net/ipv4/ip_output.c:229
 ip_finish_output+0xcaf/0xff0 net/ipv4/ip_output.c:317
 NF_HOOK_COND include/linux/netfilter.h:277 [inline]
 ip_output+0x505/0x5d0 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_queue_xmit+0x1a1d/0x1d10 net/ipv4/ip_output.c:504
 tcp_transmit_skb+0x3d6d/0x53b0 net/ipv4/tcp_output.c:1176
 __tcp_retransmit_skb+0x2fae/0x40d0 net/ipv4/tcp_output.c:2904
 tcp_send_loss_probe+0xc6f/0xf00 net/ipv4/tcp_output.c:2518
 tcp_write_timer_handler+0x5e3/0xed0 net/ipv4/tcp_timer.c:569
 tcp_write_timer+0x12b/0x280 net/ipv4/tcp_timer.c:593
 call_timer_fn+0x26a/0x5a0 kernel/time/timer.c:1326
 expire_timers kernel/time/timer.c:1363 [inline]
 __run_timers+0xda7/0x11c0 kernel/time/timer.c:1666
 run_timer_softirq+0x43/0x70 kernel/time/timer.c:1692
 __do_softirq+0x56d/0x93d kernel/softirq.c:285
Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:279 [inline]
 kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:189
 kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:315
 kmsan_slab_alloc+0x10/0x20 mm/kmsan/kmsan.c:322
 slab_post_alloc_hook mm/slab.h:446 [inline]
 slab_alloc_node mm/slub.c:2753 [inline]
 __kmalloc_node_track_caller+0xb32/0x11b0 mm/slub.c:4395
 __kmalloc_reserve net/core/skbuff.c:138 [inline]
 __alloc_skb+0x2cb/0x9e0 net/core/skbuff.c:206
 alloc_skb_fclone include/linux/skbuff.h:1030 [inline]
 sk_stream_alloc_skb+0x17c/0xcf0 net/ipv4/tcp.c:875
 tcp_fragment+0x425/0x20e0 net/ipv4/tcp_output.c:1316
 tcp_send_loss_probe+0xa69/0xf00 net/ipv4/tcp_output.c:2508
 tcp_write_timer_handler+0x5e3/0xed0 net/ipv4/tcp_timer.c:569
 tcp_write_timer+0x12b/0x280 net/ipv4/tcp_timer.c:593
 call_timer_fn+0x26a/0x5a0 kernel/time/timer.c:1326
 expire_timers kernel/time/timer.c:1363 [inline]
 __run_timers+0xda7/0x11c0 kernel/time/timer.c:1666
 run_timer_softirq+0x43/0x70 kernel/time/timer.c:1692
 __do_softirq+0x56d/0x93d kernel/softirq.c:285
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