================================================================== 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: 10823 Comm: syz-executor1 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+0x174/0x1e0 mm/kmsan/kmsan.c:1176 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: 00000000000000bf RCX: 000000000040f380 RDX: 00000000000003e8 RSI: 0000000000a3f930 RDI: 00000000000000fc RBP: 0000000000000013 R08: 0000000000000000 R09: 0000000001b61940 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000013 R13: 0000000000000004 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 ip_do_fragment+0x1b0f/0x3ed0 net/ipv4/ip_output.c:772 ip_fragment+0x248/0x3f0 net/ipv4/ip_output.c:558 ip_finish_output+0xd19/0xff0 net/ipv4/ip_output.c:315 NF_HOOK_COND include/linux/netfilter.h:277 [inline] ip_mc_output+0x1029/0x15e0 net/ipv4/ip_output.c:390 dst_output include/net/dst.h:443 [inline] ip_local_out net/ipv4/ip_output.c:124 [inline] ip_send_skb+0x5f3/0x820 net/ipv4/ip_output.c:1414 ip_push_pending_frames+0x105/0x170 net/ipv4/ip_output.c:1434 raw_sendmsg+0x2960/0x3ed0 net/ipv4/raw.c:684 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 __ip_append_data+0x107e/0x3d10 net/ipv4/ip_output.c:1057 ip_append_data+0x2fb/0x440 net/ipv4/ip_output.c:1170 raw_sendmsg+0x287b/0x3ed0 net/ipv4/raw.c:678 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 34-999 of 1000 are uninitialized ==================================================================