================================================================== BUG: KMSAN: uninit-value in copyout lib/iov_iter.c:140 [inline] BUG: KMSAN: uninit-value in _copy_to_iter+0x45f/0x2800 lib/iov_iter.c:571 CPU: 0 PID: 7652 Comm: syz-executor4 Not tainted 4.17.0-rc5+ #103 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+0x185/0x1d0 lib/dump_stack.c:113 kmsan_report+0x149/0x260 mm/kmsan/kmsan.c:1084 kmsan_internal_check_memory+0x135/0x1e0 mm/kmsan/kmsan.c:1177 kmsan_copy_to_user+0x75/0x160 mm/kmsan/kmsan.c:1219 copyout lib/iov_iter.c:140 [inline] _copy_to_iter+0x45f/0x2800 lib/iov_iter.c:571 copy_to_iter include/linux/uio.h:106 [inline] vhost_chr_read_iter+0x7b3/0xc30 drivers/vhost/vhost.c:1104 vhost_net_chr_read_iter+0xf6/0x130 drivers/vhost/net.c:1370 do_iter_readv_writev+0x84d/0xa00 include/linux/fs.h:1778 do_iter_read+0x303/0xd70 fs/read_write.c:922 vfs_readv fs/read_write.c:986 [inline] do_readv+0x295/0x5f0 fs/read_write.c:1019 __do_sys_readv fs/read_write.c:1106 [inline] __se_sys_readv fs/read_write.c:1103 [inline] __x64_sys_readv+0xe1/0x120 fs/read_write.c:1103 do_syscall_64+0x152/0x230 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x455a09 RSP: 002b:00007f4e8eb2ec68 EFLAGS: 00000246 ORIG_RAX: 0000000000000013 RAX: ffffffffffffffda RBX: 00007f4e8eb2f6d4 RCX: 0000000000455a09 RDX: 0000000000000006 RSI: 0000000020000680 RDI: 0000000000000013 RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 000000000000056b R14: 00000000006fd2a8 R15: 0000000000000000 Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:279 [inline] kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:189 kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:315 __kmalloc+0x141/0x350 mm/slub.c:3818 kmalloc include/linux/slab.h:517 [inline] vhost_new_msg drivers/vhost/vhost.c:2342 [inline] vhost_iotlb_miss drivers/vhost/vhost.c:1124 [inline] translate_desc+0xbef/0x1120 drivers/vhost/vhost.c:1831 __vhost_get_user_slow drivers/vhost/vhost.c:812 [inline] __vhost_get_user drivers/vhost/vhost.c:846 [inline] vhost_update_used_flags+0x469/0x8d0 drivers/vhost/vhost.c:1717 vhost_vq_init_access+0x173/0xa20 drivers/vhost/vhost.c:1765 vhost_net_set_backend drivers/vhost/net.c:1171 [inline] vhost_net_ioctl+0x2212/0x3450 drivers/vhost/net.c:1327 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0xaf8/0x2410 fs/ioctl.c:686 ksys_ioctl fs/ioctl.c:701 [inline] __do_sys_ioctl fs/ioctl.c:708 [inline] __se_sys_ioctl fs/ioctl.c:706 [inline] __x64_sys_ioctl+0x280/0x320 fs/ioctl.c:706 do_syscall_64+0x152/0x230 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Bytes 4-7 of 72 are uninitialized Memory access starts at ffff880132c49240 ==================================================================