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BUG: KMSAN: uninit-value in __INET_ECN_decapsulate include/net/inet_ecn.h:238 [inline]
BUG: KMSAN: uninit-value in INET_ECN_decapsulate include/net/inet_ecn.h:260 [inline]
BUG: KMSAN: uninit-value in IP6_ECN_decapsulate+0xbcd/0x24c0 include/net/inet_ecn.h:306
CPU: 1 PID: 23601 Comm: syz-executor.4 Not tainted 5.10.0-rc4-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+0x21c/0x280 lib/dump_stack.c:118
 kmsan_report+0xfb/0x1e0 mm/kmsan/kmsan_report.c:118
 __msan_warning+0x5f/0xa0 mm/kmsan/kmsan_instr.c:197
 __INET_ECN_decapsulate include/net/inet_ecn.h:238 [inline]
 INET_ECN_decapsulate include/net/inet_ecn.h:260 [inline]
 IP6_ECN_decapsulate+0xbcd/0x24c0 include/net/inet_ecn.h:306
 ip6ip6_dscp_ecn_decapsulate+0x1fa/0x260 net/ipv6/ip6_tunnel.c:761
 __ip6_tnl_rcv+0x10eb/0x19d0 net/ipv6/ip6_tunnel.c:879
 ip6_tnl_rcv+0x180/0x1c0 net/ipv6/ip6_tunnel.c:926
 gre_rcv+0x1764/0x1bd0 net/ipv6/ip6_gre.c:518
 ip6_protocol_deliver_rcu+0x1402/0x25e0 net/ipv6/ip6_input.c:433
 ip6_input_finish net/ipv6/ip6_input.c:474 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 ip6_input+0x12b/0x390 net/ipv6/ip6_input.c:483
 dst_input include/net/dst.h:449 [inline]
 ip6_rcv_finish+0x5fc/0x7f0 net/ipv6/ip6_input.c:76
 NF_HOOK include/linux/netfilter.h:301 [inline]
 ipv6_rcv+0x1d1/0x460 net/ipv6/ip6_input.c:307
 __netif_receive_skb_one_core net/core/dev.c:5315 [inline]
 __netif_receive_skb+0x1ec/0x640 net/core/dev.c:5429
 netif_receive_skb_internal+0x1ae/0x3e0 net/core/dev.c:5534
 netif_receive_skb+0x4c/0x270 net/core/dev.c:5593
 tun_rx_batched include/linux/skbuff.h:4351 [inline]
 tun_get_user+0x63b2/0x66a0 drivers/net/tun.c:1939
 tun_chr_write_iter+0x1f3/0x360 drivers/net/tun.c:1968
 call_write_iter include/linux/fs.h:1903 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x1083/0x1b00 fs/read_write.c:605
 ksys_write+0x275/0x500 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write+0x92/0xb0 fs/read_write.c:667
 __ia32_sys_write+0x4a/0x70 fs/read_write.c:667
 do_syscall_32_irqs_on arch/x86/entry/common.c:80 [inline]
 __do_fast_syscall_32+0x102/0x160 arch/x86/entry/common.c:139
 do_fast_syscall_32+0x6a/0xc0 arch/x86/entry/common.c:162
 do_SYSENTER_32+0x73/0x90 arch/x86/entry/common.c:205
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
RIP: 0023:0xf7f54549
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 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:00000000f554e0c4 EFLAGS: 00000296 ORIG_RAX: 0000000000000004
RAX: ffffffffffffffda RBX: 00000000000000f0 RCX: 0000000020000080
RDX: 000000000000005c RSI: 0000000008baafe0 RDI: 0000000008baafe0
RBP: 00000000f554e228 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Uninit was created at:
 kmsan_save_stack_with_flags+0x3c/0x90 mm/kmsan/kmsan.c:121
 kmsan_alloc_page+0xd3/0x1f0 mm/kmsan/kmsan_shadow.c:274
 __alloc_pages_nodemask+0x827/0xf90 mm/page_alloc.c:4989
 alloc_pages_current+0x7b6/0xb60 mm/mempolicy.c:2271
 alloc_pages include/linux/gfp.h:547 [inline]
 skb_page_frag_refill+0x194/0x790 net/core/sock.c:2460
 tun_build_skb+0x23d/0x1ad0 drivers/net/tun.c:1609
 tun_get_user+0x1473/0x66a0 drivers/net/tun.c:1753
 tun_chr_write_iter+0x1f3/0x360 drivers/net/tun.c:1968
 call_write_iter include/linux/fs.h:1903 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x1083/0x1b00 fs/read_write.c:605
 ksys_write+0x275/0x500 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write+0x92/0xb0 fs/read_write.c:667
 __ia32_sys_write+0x4a/0x70 fs/read_write.c:667
 do_syscall_32_irqs_on arch/x86/entry/common.c:80 [inline]
 __do_fast_syscall_32+0x102/0x160 arch/x86/entry/common.c:139
 do_fast_syscall_32+0x6a/0xc0 arch/x86/entry/common.c:162
 do_SYSENTER_32+0x73/0x90 arch/x86/entry/common.c:205
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
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