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BUG: KMSAN: kernel-infoleak in __copy_to_user include/linux/uaccess.h:121 [inline]
BUG: KMSAN: kernel-infoleak in __kvm_write_guest_page arch/x86/kvm/../../../virt/kvm/kvm_main.c:1849 [inline]
BUG: KMSAN: kernel-infoleak in kvm_vcpu_write_guest_page+0x383/0x500 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1870
CPU: 1 PID: 8023 Comm: syz-executor4 Not tainted 4.19.0-rc7+ #69
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+0x306/0x460 lib/dump_stack.c:113
 kmsan_report+0x1a2/0x2e0 mm/kmsan/kmsan.c:917
 kmsan_internal_check_memory+0x374/0x460 mm/kmsan/kmsan.c:997
 kmsan_copy_to_user+0x89/0xe0 mm/kmsan/kmsan_hooks.c:552
 __copy_to_user include/linux/uaccess.h:121 [inline]
 __kvm_write_guest_page arch/x86/kvm/../../../virt/kvm/kvm_main.c:1849 [inline]
 kvm_vcpu_write_guest_page+0x383/0x500 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1870
 kvm_vcpu_write_guest+0x1d6/0x350 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1904
 emulator_write_phys arch/x86/kvm/x86.c:5061 [inline]
 write_emulate+0xce/0x180 arch/x86/kvm/x86.c:5101
 emulator_read_write_onepage+0x1280/0x1d20 arch/x86/kvm/x86.c:5170
 emulator_read_write+0x505/0x9f0 arch/x86/kvm/x86.c:5225
 emulator_write_emulated+0xf7/0x110 arch/x86/kvm/x86.c:5262
 segmented_write arch/x86/kvm/emulate.c:1446 [inline]
 writeback+0xe21/0x1060 arch/x86/kvm/emulate.c:1814
 x86_emulate_insn+0x5e97/0xa5b0 arch/x86/kvm/emulate.c:5673
 x86_emulate_instruction+0x14e6/0x6360 arch/x86/kvm/x86.c:6237
 kvm_mmu_page_fault+0xd24/0x2ae0 arch/x86/kvm/mmu.c:5296
 handle_ept_violation+0x7e1/0x820 arch/x86/kvm/vmx.c:7689
 vmx_handle_exit+0x20f5/0xb900 arch/x86/kvm/vmx.c:10129
 vcpu_enter_guest arch/x86/kvm/x86.c:7667 [inline]
 vcpu_run arch/x86/kvm/x86.c:7730 [inline]
 kvm_arch_vcpu_ioctl_run+0xa22b/0x10ab0 arch/x86/kvm/x86.c:7930
 kvm_vcpu_ioctl+0x11a7/0x20b0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2590
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0xf28/0x2ca0 fs/ioctl.c:687
 ksys_ioctl fs/ioctl.c:702 [inline]
 __do_sys_ioctl fs/ioctl.c:709 [inline]
 __se_sys_ioctl+0x1da/0x270 fs/ioctl.c:707
 __x64_sys_ioctl+0x4a/0x70 fs/ioctl.c:707
 do_syscall_64+0xbe/0x100 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x457569
Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f7d042bec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457569
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000007
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f7d042bf6d4
R13: 00000000004c0027 R14: 00000000004d0108 R15: 00000000ffffffff

Uninit was stored to memory at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:255 [inline]
 kmsan_save_stack mm/kmsan/kmsan.c:270 [inline]
 kmsan_internal_chain_origin+0x136/0x240 mm/kmsan/kmsan.c:572
 __msan_chain_origin+0x75/0xd0 mm/kmsan/kmsan_instr.c:337
 em_fnstcw+0x21f/0x240 arch/x86/kvm/emulate.c:1161
 x86_emulate_insn+0x2d48/0xa5b0 arch/x86/kvm/emulate.c:5592
 x86_emulate_instruction+0x14e6/0x6360 arch/x86/kvm/x86.c:6237
 kvm_mmu_page_fault+0xd24/0x2ae0 arch/x86/kvm/mmu.c:5296
 handle_ept_violation+0x7e1/0x820 arch/x86/kvm/vmx.c:7689
 vmx_handle_exit+0x20f5/0xb900 arch/x86/kvm/vmx.c:10129
 vcpu_enter_guest arch/x86/kvm/x86.c:7667 [inline]
 vcpu_run arch/x86/kvm/x86.c:7730 [inline]
 kvm_arch_vcpu_ioctl_run+0xa22b/0x10ab0 arch/x86/kvm/x86.c:7930
 kvm_vcpu_ioctl+0x11a7/0x20b0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2590
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0xf28/0x2ca0 fs/ioctl.c:687
 ksys_ioctl fs/ioctl.c:702 [inline]
 __do_sys_ioctl fs/ioctl.c:709 [inline]
 __se_sys_ioctl+0x1da/0x270 fs/ioctl.c:707
 __x64_sys_ioctl+0x4a/0x70 fs/ioctl.c:707
 do_syscall_64+0xbe/0x100 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7

Local variable description: ----fcw@em_fnstcw
Variable was created at:
 em_fnstcw+0x4a/0x240 arch/x86/kvm/emulate.c:1153
 x86_emulate_insn+0x2d48/0xa5b0 arch/x86/kvm/emulate.c:5592

Bytes 0-1 of 2 are uninitialized
Memory access of size 2 starts at ffff880130cfb920
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