================================================================== 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: 1 PID: 6855 Comm: syz-executor7 Not tainted 4.16.0+ #85 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+0x2ae4/0x3280 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+0x7dd/0x9b0 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: 0033:0x40f3e0 RSP: 002b:0000000000a3eaa8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 000000000000000b RCX: 000000000040f3e0 RDX: 00000000000003e8 RSI: 0000000000a3f930 RDI: 00000000000000fc RBP: 0000000000000013 R08: 0000000000000000 R09: 0000000001582940 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000013 R13: 0000000000000000 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 __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:528 udp_send_skb+0x108b/0x1310 net/ipv4/udp.c:804 udp_push_pending_frames net/ipv4/udp.c:837 [inline] udp_sendpage+0x726/0x960 net/ipv4/udp.c:1155 inet_sendpage+0x4ea/0x8c0 net/ipv4/af_inet.c:781 kernel_sendpage net/socket.c:3234 [inline] sock_sendpage+0x1de/0x2c0 net/socket.c:855 pipe_to_sendpage+0x31b/0x430 fs/splice.c:451 splice_from_pipe_feed fs/splice.c:502 [inline] __splice_from_pipe+0x49a/0xf30 fs/splice.c:626 splice_from_pipe fs/splice.c:661 [inline] generic_splice_sendpage+0x1c6/0x2a0 fs/splice.c:832 do_splice_from fs/splice.c:851 [inline] direct_splice_actor+0x19b/0x200 fs/splice.c:1018 splice_direct_to_actor+0x764/0x1040 fs/splice.c:973 do_splice_direct+0x335/0x540 fs/splice.c:1061 do_sendfile+0x1067/0x1e40 fs/read_write.c:1413 SYSC_sendfile64+0x297/0x300 fs/read_write.c:1474 SyS_sendfile64+0x64/0x90 fs/read_write.c:1460 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 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 __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:528 ip_append_page+0x1174/0x1fc0 net/ipv4/ip_output.c:1287 udp_sendpage+0x2d6/0x960 net/ipv4/udp.c:1141 inet_sendpage+0x4ea/0x8c0 net/ipv4/af_inet.c:781 kernel_sendpage net/socket.c:3234 [inline] sock_sendpage+0x1de/0x2c0 net/socket.c:855 pipe_to_sendpage+0x31b/0x430 fs/splice.c:451 splice_from_pipe_feed fs/splice.c:502 [inline] __splice_from_pipe+0x49a/0xf30 fs/splice.c:626 splice_from_pipe fs/splice.c:661 [inline] generic_splice_sendpage+0x1c6/0x2a0 fs/splice.c:832 do_splice_from fs/splice.c:851 [inline] direct_splice_actor+0x19b/0x200 fs/splice.c:1018 splice_direct_to_actor+0x764/0x1040 fs/splice.c:973 do_splice_direct+0x335/0x540 fs/splice.c:1061 do_sendfile+0x1067/0x1e40 fs/read_write.c:1413 SYSC_sendfile64+0x297/0x300 fs/read_write.c:1474 SyS_sendfile64+0x64/0x90 fs/read_write.c:1460 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_vma+0xcc8/0x1800 mm/mempolicy.c:2019 shmem_alloc_page mm/shmem.c:1471 [inline] shmem_alloc_and_acct_page+0x6d5/0x1000 mm/shmem.c:1496 shmem_getpage_gfp+0x35db/0x5770 mm/shmem.c:1771 shmem_getpage mm/shmem.c:131 [inline] shmem_file_read_iter+0x508/0x1180 mm/shmem.c:2456 call_read_iter include/linux/fs.h:1776 [inline] generic_file_splice_read+0x5d2/0x900 fs/splice.c:307 do_splice_to fs/splice.c:880 [inline] splice_direct_to_actor+0x4c6/0x1040 fs/splice.c:952 do_splice_direct+0x335/0x540 fs/splice.c:1061 do_sendfile+0x1067/0x1e40 fs/read_write.c:1413 SYSC_sendfile64+0x297/0x300 fs/read_write.c:1474 SyS_sendfile64+0x64/0x90 fs/read_write.c:1460 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 Bytes 40-41 of 42 are uninitialized ==================================================================