syzbot

L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html for details.
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BUG: KMSAN: kernel-infoleak in __copy_to_user include/linux/uaccess.h:118 [inline]
BUG: KMSAN: kernel-infoleak in __kvm_write_guest_page+0x2cb/0x420 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2009
CPU: 1 PID: 13501 Comm: syz-executor659 Not tainted 5.2.0-rc4+ #7
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+0x191/0x1f0 lib/dump_stack.c:113
 kmsan_report+0x162/0x2d0 mm/kmsan/kmsan.c:611
 kmsan_internal_check_memory+0x974/0xa80 mm/kmsan/kmsan.c:705
 kmsan_copy_to_user+0xa9/0xb0 mm/kmsan/kmsan_hooks.c:496
 __copy_to_user include/linux/uaccess.h:118 [inline]
 __kvm_write_guest_page+0x2cb/0x420 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2009
 kvm_vcpu_write_guest_page+0x5f8/0x630 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2030
 kvm_vcpu_write_guest+0x1e0/0x360 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2064
 kvm_write_guest_virt_helper arch/x86/kvm/x86.c:5233 [inline]
 emulator_write_std+0x391/0x4d0 arch/x86/kvm/x86.c:5257
 segmented_write_std arch/x86/kvm/emulate.c:853 [inline]
 em_fxsave+0x7c8/0x850 arch/x86/kvm/emulate.c:4086
 x86_emulate_insn+0x201d/0xa800 arch/x86/kvm/emulate.c:5614
 x86_emulate_instruction+0x1012/0x71d0 arch/x86/kvm/x86.c:6509
 kvm_mmu_page_fault+0xce4/0x2950 arch/x86/kvm/mmu.c:5430
 handle_ept_violation+0x478/0x4e0 arch/x86/kvm/vmx/vmx.c:5099
 vmx_handle_exit+0x1280/0x20c0 arch/x86/kvm/vmx/vmx.c:5861
 vcpu_enter_guest arch/x86/kvm/x86.c:8035 [inline]
 vcpu_run arch/x86/kvm/x86.c:8099 [inline]
 kvm_arch_vcpu_ioctl_run+0x9e3a/0xd430 arch/x86/kvm/x86.c:8307
 kvm_vcpu_ioctl+0x1099/0x1d00 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2755
 do_vfs_ioctl+0xea8/0x2c50 fs/ioctl.c:46
 ksys_ioctl fs/ioctl.c:713 [inline]
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl+0x1da/0x270 fs/ioctl.c:718
 __x64_sys_ioctl+0x4a/0x70 fs/ioctl.c:718
 do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:302
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x4431f9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 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 1b 0c fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffe590eeac8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffe590eead0 RCX: 00000000004431f9
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000400f50 R09: 0000000000400f50
R10: fffffffffffffffe R11: 0000000000000246 R12: 00000000004042a0
R13: 0000000000404330 R14: 0000000000000000 R15: 0000000000000000

Local variable description: ----fx_state@em_fxsave
Variable was created at:
 check_fxsr arch/x86/kvm/emulate.c:4073 [inline]
 em_fxsave+0x5c/0x850 arch/x86/kvm/emulate.c:4077
 x86_emulate_insn+0x201d/0xa800 arch/x86/kvm/emulate.c:5614

Bytes 8-159 of 160 are uninitialized
Memory access of size 160 starts at ffff8880a748f0a0
Data copied to user address 0000000020000000
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