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BUG: KMSAN: uninit-value in __sctp_rcv_walk_lookup net/sctp/input.c:1208 [inline]
BUG: KMSAN: uninit-value in __sctp_rcv_lookup_harder net/sctp/input.c:1287 [inline]
BUG: KMSAN: uninit-value in __sctp_rcv_lookup net/sctp/input.c:1307 [inline]
BUG: KMSAN: uninit-value in sctp_rcv+0x2b2d/0x5410 net/sctp/input.c:159
CPU: 1 PID: 31273 Comm: syz-executor.5 Not tainted 5.6.0-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+0x1c9/0x220 lib/dump_stack.c:118
 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118
 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
 __sctp_rcv_walk_lookup net/sctp/input.c:1208 [inline]
 __sctp_rcv_lookup_harder net/sctp/input.c:1287 [inline]
 __sctp_rcv_lookup net/sctp/input.c:1307 [inline]
 sctp_rcv+0x2b2d/0x5410 net/sctp/input.c:159
 ip_protocol_deliver_rcu+0x700/0xbc0 net/ipv4/ip_input.c:204
 ip_local_deliver_finish net/ipv4/ip_input.c:231 [inline]
 NF_HOOK include/linux/netfilter.h:307 [inline]
 ip_local_deliver+0x62a/0x7c0 net/ipv4/ip_input.c:252
 dst_input include/net/dst.h:442 [inline]
 ip_rcv_finish net/ipv4/ip_input.c:428 [inline]
 NF_HOOK include/linux/netfilter.h:307 [inline]
 ip_rcv+0x6cf/0x750 net/ipv4/ip_input.c:538
 __netif_receive_skb_one_core net/core/dev.c:5187 [inline]
 __netif_receive_skb net/core/dev.c:5301 [inline]
 netif_receive_skb_internal net/core/dev.c:5391 [inline]
 netif_receive_skb+0xbb5/0xf20 net/core/dev.c:5450
 tun_rx_batched include/linux/skbuff.h:4351 [inline]
 tun_get_user+0x6aef/0x6f60 drivers/net/tun.c:1997
 tun_chr_write_iter+0x1f2/0x360 drivers/net/tun.c:2026
 call_write_iter include/linux/fs.h:1902 [inline]
 new_sync_write fs/read_write.c:483 [inline]
 __vfs_write+0xa5a/0xca0 fs/read_write.c:496
 vfs_write+0x44a/0x8f0 fs/read_write.c:558
 ksys_write+0x267/0x450 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write+0x92/0xb0 fs/read_write.c:620
 __x64_sys_write+0x4a/0x70 fs/read_write.c:620
 do_syscall_64+0xb8/0x160 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45c829
Code: 0d b7 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 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f73c3e4bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000050ce80 RCX: 000000000045c829
RDX: 000000000000fdef RSI: 0000000020000240 RDI: 0000000000000003
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000d0f R14: 00000000004cf3ff R15: 00007f73c3e4c6d4

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline]
 kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:127
 kmsan_slab_alloc+0x8a/0xe0 mm/kmsan/kmsan_hooks.c:80
 slab_alloc_node mm/slub.c:2801 [inline]
 __kmalloc_node_track_caller+0xb40/0x1200 mm/slub.c:4420
 __kmalloc_reserve net/core/skbuff.c:142 [inline]
 __alloc_skb+0x2fd/0xac0 net/core/skbuff.c:210
 alloc_skb include/linux/skbuff.h:1081 [inline]
 alloc_skb_with_frags+0x18c/0xa70 net/core/skbuff.c:5764
 sock_alloc_send_pskb+0xada/0xc60 net/core/sock.c:2245
 tun_alloc_skb drivers/net/tun.c:1529 [inline]
 tun_get_user+0x10ae/0x6f60 drivers/net/tun.c:1843
 tun_chr_write_iter+0x1f2/0x360 drivers/net/tun.c:2026
 call_write_iter include/linux/fs.h:1902 [inline]
 new_sync_write fs/read_write.c:483 [inline]
 __vfs_write+0xa5a/0xca0 fs/read_write.c:496
 vfs_write+0x44a/0x8f0 fs/read_write.c:558
 ksys_write+0x267/0x450 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write+0x92/0xb0 fs/read_write.c:620
 __x64_sys_write+0x4a/0x70 fs/read_write.c:620
 do_syscall_64+0xb8/0x160 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
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