KMSAN: uninit-value in vmx_queue_exception

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    2808e543aacb kmsan: use __memmove() in fixup_bad_iret()
git tree:       https://github.com/google/kmsan.git/master
console output: https://syzkaller.appspot.com/x/log.txt?x=171e8f7b400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c73fa4249092e6f1
dashboard link: https://syzkaller.appspot.com/bug?extid=788c6e0a154504bd4b99
compiler:       clang version 8.0.0 (trunk 343298)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16a0ac5d400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=113a6f7b400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+788c6e0a154504bd4b99@xxxxxxxxxxxxxxxxxxxxxxxxx

L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and  
https://www.kernel.org/doc/html/latest/admin-guide/l1tf.html for details.
==================================================================
BUG: KMSAN: uninit-value in __vmcs_writel arch/x86/kvm/vmx.c:2399 [inline]
BUG: KMSAN: uninit-value in vmcs_write32 arch/x86/kvm/vmx.c:2420 [inline]
BUG: KMSAN: uninit-value in vmx_queue_exception+0x757/0x920  
arch/x86/kvm/vmx.c:3352
CPU: 0 PID: 6638 Comm: syz-executor166 Not tainted 4.20.0-rc3+ #89
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+0x32d/0x480 lib/dump_stack.c:113
 kmsan_report+0x19f/0x300 mm/kmsan/kmsan.c:911
 __msan_warning+0x76/0xc0 mm/kmsan/kmsan_instr.c:415
 __vmcs_writel arch/x86/kvm/vmx.c:2399 [inline]
 vmcs_write32 arch/x86/kvm/vmx.c:2420 [inline]
 vmx_queue_exception+0x757/0x920 arch/x86/kvm/vmx.c:3352
 inject_pending_event arch/x86/kvm/x86.c:7146 [inline]
 vcpu_enter_guest arch/x86/kvm/x86.c:7641 [inline]
 vcpu_run arch/x86/kvm/x86.c:7872 [inline]
 kvm_arch_vcpu_ioctl_run+0x7d81/0x12040 arch/x86/kvm/x86.c:8072
 kvm_vcpu_ioctl+0xfb1/0x1f90 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2596
 do_vfs_ioctl+0xfbc/0x2f70 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+0xcf/0x110 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x442a39
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:00007ffef8ea1048 EFLAGS: 00000217 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000442a39
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 00000000006cd018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 0000000020014000 R11: 0000000000000217 R12: 0000000000403ae0
R13: 0000000000403b70 R14: 0000000000000000 R15: 0000000000000000

Uninit was stored to memory at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:252 [inline]
 kmsan_save_stack mm/kmsan/kmsan.c:267 [inline]
 kmsan_internal_chain_origin+0x136/0x240 mm/kmsan/kmsan.c:569
 __msan_chain_origin+0x6d/0xb0 mm/kmsan/kmsan_instr.c:292
 kvm_multiple_exception arch/x86/kvm/x86.c:483 [inline]
 kvm_queue_exception_e_p arch/x86/kvm/x86.c:554 [inline]
 kvm_inject_page_fault+0xa60/0xef0 arch/x86/kvm/x86.c:578
 nested_vmx_get_vmptr+0x36f/0x3d0 arch/x86/kvm/vmx.c:8264
 handle_vmon+0x5ea/0xe70 arch/x86/kvm/vmx.c:8387
 vmx_handle_exit+0x21bd/0xb980 arch/x86/kvm/vmx.c:10600
 vcpu_enter_guest arch/x86/kvm/x86.c:7809 [inline]
 vcpu_run arch/x86/kvm/x86.c:7872 [inline]
 kvm_arch_vcpu_ioctl_run+0xaeee/0x12040 arch/x86/kvm/x86.c:8072
 kvm_vcpu_ioctl+0xfb1/0x1f90 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2596
 do_vfs_ioctl+0xfbc/0x2f70 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+0xcf/0x110 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7

Local variable description: ----e@nested_vmx_get_vmptr
Variable was created at:
 nested_vmx_get_vmptr+0xa5/0x3d0 arch/x86/kvm/vmx.c:8255
 handle_vmon+0x5ea/0xe70 arch/x86/kvm/vmx.c:8387
==================================================================


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