================================================================== BUG: KMSAN: uninit-value in copyout lib/iov_iter.c:140 [inline] BUG: KMSAN: uninit-value in _copy_to_iter+0x46d/0x28f0 lib/iov_iter.c:571 CPU: 0 PID: 7096 Comm: syz-executor4 Not tainted 4.16.0+ #84 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x185/0x1d0 lib/dump_stack.c:53 kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067 kmsan_internal_check_memory+0xfb/0x1e0 mm/kmsan/kmsan.c:1170 kmsan_copy_to_user+0x69/0x160 mm/kmsan/kmsan.c:1199 copyout lib/iov_iter.c:140 [inline] _copy_to_iter+0x46d/0x28f0 lib/iov_iter.c:571 copy_to_iter include/linux/uio.h:106 [inline] skb_copy_datagram_iter+0x443/0xf70 net/core/datagram.c:431 tun_put_user drivers/net/tun.c:2111 [inline] tun_do_read+0x2a29/0x30c0 drivers/net/tun.c:2195 tun_chr_read_iter+0x21f/0x460 drivers/net/tun.c:2214 call_read_iter include/linux/fs.h:1776 [inline] new_sync_read fs/read_write.c:401 [inline] __vfs_read+0x6fb/0x8e0 fs/read_write.c:413 vfs_read+0x36c/0x6c0 fs/read_write.c:447 SYSC_read+0x172/0x360 fs/read_write.c:573 SyS_read+0x55/0x80 fs/read_write.c:566 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 RIP: 0033:0x40f380 RSP: 002b:0000000000a3eaa8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 000000000000001e RCX: 000000000040f380 RDX: 00000000000003e8 RSI: 0000000000a3f930 RDI: 00000000000000fc RBP: 0000000000000013 R08: 0000000000000000 R09: 0000000000c93940 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000013 R13: 0000000000000011 R14: 0000000000000000 R15: 0000000000001380 Uninit was stored to memory at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline] kmsan_save_stack mm/kmsan/kmsan.c:293 [inline] kmsan_internal_chain_origin+0x12b/0x210 mm/kmsan/kmsan.c:684 kmsan_memcpy_origins+0x11d/0x170 mm/kmsan/kmsan.c:526 __msan_memcpy+0x19f/0x1f0 mm/kmsan/kmsan_instr.c:470 skb_copy_bits+0x63a/0xdb0 net/core/skbuff.c:2046 skb_copy_bits+0xac8/0xdb0 net/core/skbuff.c:2067 ip6_fragment+0x4526/0x5150 net/ipv6/ip6_output.c:849 ip6_finish_output+0x96c/0xc00 net/ipv6/ip6_output.c:152 NF_HOOK_COND include/linux/netfilter.h:277 [inline] ip6_output+0x597/0x6c0 net/ipv6/ip6_output.c:171 dst_output include/net/dst.h:443 [inline] ip6_local_out+0x573/0x640 net/ipv6/output_core.c:176 ip6_send_skb+0xfa/0x380 net/ipv6/ip6_output.c:1682 udp_v6_send_skb+0x116a/0x1880 net/ipv6/udp.c:1044 udp_v6_push_pending_frames net/ipv6/udp.c:1077 [inline] udpv6_sendmsg+0x15f4/0x45b0 net/ipv6/udp.c:1343 inet_sendmsg+0x48d/0x740 net/ipv4/af_inet.c:764 sock_sendmsg_nosec net/socket.c:630 [inline] sock_sendmsg net/socket.c:640 [inline] SYSC_sendto+0x6c3/0x7e0 net/socket.c:1747 SyS_sendto+0x8a/0xb0 net/socket.c:1715 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline] kmsan_alloc_meta_for_pages+0x161/0x3a0 mm/kmsan/kmsan.c:814 kmsan_alloc_page+0x82/0xe0 mm/kmsan/kmsan.c:868 __alloc_pages_nodemask+0xf5b/0x5dc0 mm/page_alloc.c:4283 alloc_pages_current+0x6b5/0x970 mm/mempolicy.c:2055 alloc_pages include/linux/gfp.h:494 [inline] skb_page_frag_refill+0x3ba/0x5e0 net/core/sock.c:2208 sk_page_frag_refill+0xa4/0x340 net/core/sock.c:2228 __ip6_append_data+0x1a20/0x4bb0 net/ipv6/ip6_output.c:1503 ip6_append_data+0x40e/0x6b0 net/ipv6/ip6_output.c:1576 udpv6_sendmsg+0xfd5/0x45b0 net/ipv6/udp.c:1337 inet_sendmsg+0x48d/0x740 net/ipv4/af_inet.c:764 sock_sendmsg_nosec net/socket.c:630 [inline] sock_sendmsg net/socket.c:640 [inline] SYSC_sendto+0x6c3/0x7e0 net/socket.c:1747 SyS_sendto+0x8a/0xb0 net/socket.c:1715 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 Bytes 83-101 of 103 are uninitialized ==================================================================