syzbot

random: crng init done
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BUG: KMSAN: uninit-value in do_csum lib/checksum.c:69 [inline]
BUG: KMSAN: uninit-value in ip_fast_csum+0x444/0x460 lib/checksum.c:112
CPU: 0 PID: 8 Comm: ksoftirqd/0 Not tainted 4.17.0+ #16
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+0x188/0x2a0 mm/kmsan/kmsan.c:1352
 __msan_warning_32+0x70/0xc0 mm/kmsan/kmsan_instr.c:634
 do_csum lib/checksum.c:69 [inline]
 ip_fast_csum+0x444/0x460 lib/checksum.c:112
 inet_gro_receive+0x6c9/0x1950 net/ipv4/af_inet.c:1418
 dev_gro_receive+0x214c/0x32e0 net/core/dev.c:4989
 napi_gro_receive+0x624/0xb60 net/core/dev.c:5124
 receive_buf+0x4c96/0x6ae0 drivers/net/virtio_net.c:945
 virtnet_receive drivers/net/virtio_net.c:1200 [inline]
 virtnet_poll+0x8ff/0x1420 drivers/net/virtio_net.c:1282
 napi_poll net/core/dev.c:5735 [inline]
 net_rx_action+0x766/0x1a80 net/core/dev.c:5801
 __do_softirq+0x592/0x979 kernel/softirq.c:285
 run_ksoftirqd+0x24/0x40 kernel/softirq.c:649
 smpboot_thread_fn+0x4ac/0x9a0 kernel/smpboot.c:164
 kthread+0x4db/0x6c0 kernel/kthread.c:241
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:415

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:287 [inline]
 kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:197
 kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:323
 kmem_cache_alloc+0xa97/0xb70 mm/slub.c:2772
 __build_skb net/core/skbuff.c:282 [inline]
 __napi_alloc_skb+0x27c/0xa10 net/core/skbuff.c:483
 napi_alloc_skb include/linux/skbuff.h:2655 [inline]
 page_to_skb+0x141/0x1190 drivers/net/virtio_net.c:349
 receive_mergeable drivers/net/virtio_net.c:812 [inline]
 receive_buf+0xc98/0x6ae0 drivers/net/virtio_net.c:917
 virtnet_receive drivers/net/virtio_net.c:1200 [inline]
 virtnet_poll+0x8ff/0x1420 drivers/net/virtio_net.c:1282
 napi_poll net/core/dev.c:5735 [inline]
 net_rx_action+0x766/0x1a80 net/core/dev.c:5801
 __do_softirq+0x592/0x979 kernel/softirq.c:285
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