Re: [PATCH 1/2] KVM: x86: Check hypercall's exit to userspace generically

[kernel test robot]

Hello,

kernel test robot noticed "UBSAN:shift-out-of-bounds_in_arch/x86/kvm#h" on:

commit: 1635eb4564804d324e91d78e8e5ed206e006e3a6 ("[PATCH 1/2] KVM: x86: Check hypercall's exit to userspace generically")
url: https://github.com/intel-lab-lkp/linux/commits/Binbin-Wu/KVM-x86-Check-hypercall-s-exit-to-userspace-generically/20240708-172555
patch link: https://lore.kernel.org/all/20240708092150.1799371-2-binbin.wu@xxxxxxxxxxxxxxx/
patch subject: [PATCH 1/2] KVM: x86: Check hypercall's exit to userspace generically

in testcase: kvm-unit-tests-qemu
version: 
with following parameters:




compiler: gcc-13
test machine: 128 threads 2 sockets Intel(R) Xeon(R) Platinum 8358 CPU @ 2.60GHz (Ice Lake) with 128G memory

(please refer to attached dmesg/kmsg for entire log/backtrace)



If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-lkp/202407242159.893be500-oliver.sang@xxxxxxxxx


[  414.980354][T21255] ------------[ cut here ]------------
[  414.989024][T21255] UBSAN: shift-out-of-bounds in arch/x86/kvm/x86.h:552:47
[  415.001167][T21255] shift exponent 4294967295 is too large for 32-bit type 'int'
[  415.011803][T21255] CPU: 107 PID: 21255 Comm: qemu-system-x86 Not tainted 6.10.0-rc2-00186-g1635eb456480 #1
[  415.024716][T21255] Call Trace:
[  415.030982][T21255]  <TASK>
[415.036836][T21255] dump_stack_lvl (lib/dump_stack.c:117) 
[415.044268][T21255] __ubsan_handle_shift_out_of_bounds (lib/ubsan.c:232 lib/ubsan.c:468) 
[415.053610][T21255] kvm_emulate_hypercall.cold (include/trace/events/kvm.h:213 (discriminator 6)) kvm
[415.063097][T21255] ? __pfx_kvm_emulate_hypercall (arch/x86/kvm/x86.c:10206) kvm
[415.073104][T21255] ? __vmx_handle_exit (arch/x86/kvm/vmx/vmx.c:6469) kvm_intel
[415.082284][T21255] vmx_handle_exit (arch/x86/kvm/vmx/vmx.c:6632 (discriminator 1)) kvm_intel
[415.090893][T21255] vcpu_enter_guest+0x130f/0x3350 kvm
[415.100855][T21255] ? vmx_segment_cache_test_set (arch/x86/include/asm/bitops.h:206 (discriminator 1) arch/x86/include/asm/bitops.h:238 (discriminator 1) include/asm-generic/bitops/instrumented-non-atomic.h:142 (discriminator 1) arch/x86/kvm/vmx/../kvm_cache_regs.h:56 (discriminator 1) arch/x86/kvm/vmx/vmx.c:825 (discriminator 1)) kvm_intel
[415.110593][T21255] ? __pfx_vcpu_enter_guest+0x10/0x10 kvm
[415.120837][T21255] ? vmx_read_guest_seg_ar (arch/x86/kvm/vmx/vmx.c:865 (discriminator 1)) kvm_intel
[415.130124][T21255] ? skip_emulated_instruction (arch/x86/kvm/vmx/vmx.c:1775) kvm_intel
[415.139821][T21255] ? __pfx_skip_emulated_instruction (arch/x86/kvm/vmx/vmx.c:1715) kvm_intel
[415.149853][T21255] ? __pfx_kvm_get_linear_rip (arch/x86/kvm/x86.c:13256) kvm
[415.159211][T21255] vcpu_run (arch/x86/kvm/x86.c:11311) kvm
[415.167028][T21255] kvm_arch_vcpu_ioctl_run (arch/x86/kvm/x86.c:11537) kvm
[415.176327][T21255] ? __pfx_do_vfs_ioctl (fs/ioctl.c:805) 
[415.184065][T21255] kvm_vcpu_ioctl (arch/x86/kvm/../../../virt/kvm/kvm_main.c:4440) kvm
[415.192450][T21255] ? __pfx_kvm_vcpu_ioctl (arch/x86/kvm/../../../virt/kvm/kvm_main.c:4394) kvm
[415.201351][T21255] ? down_read_trylock (arch/x86/include/asm/atomic64_64.h:20 include/linux/atomic/atomic-arch-fallback.h:2629 include/linux/atomic/atomic-long.h:79 include/linux/atomic/atomic-instrumented.h:3224 kernel/locking/rwsem.c:176 kernel/locking/rwsem.c:181 kernel/locking/rwsem.c:1288 kernel/locking/rwsem.c:1565) 
[415.209117][T21255] ? __fget_light (fs/file.c:1154) 
[415.216411][T21255] ? fput (arch/x86/include/asm/atomic64_64.h:61 (discriminator 1) include/linux/atomic/atomic-arch-fallback.h:4404 (discriminator 1) include/linux/atomic/atomic-long.h:1571 (discriminator 1) include/linux/atomic/atomic-instrumented.h:4540 (discriminator 1) fs/file_table.c:473 (discriminator 1)) 
[415.222864][T21255] ? __fget_light (fs/file.c:1154) 
[415.230119][T21255] __x64_sys_ioctl (fs/ioctl.c:51 fs/ioctl.c:907 fs/ioctl.c:893 fs/ioctl.c:893) 
[415.237407][T21255] do_syscall_64 (arch/x86/entry/common.c:52 (discriminator 1) arch/x86/entry/common.c:83 (discriminator 1)) 
[415.244400][T21255] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) 
[  415.252801][T21255] RIP: 0033:0x7f12912f8c5b
[ 415.259801][T21255] Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00
All code
========
   0:	00 48 89             	add    %cl,-0x77(%rax)
   3:	44 24 18             	rex.R and $0x18,%al
   6:	31 c0                	xor    %eax,%eax
   8:	48 8d 44 24 60       	lea    0x60(%rsp),%rax
   d:	c7 04 24 10 00 00 00 	movl   $0x10,(%rsp)
  14:	48 89 44 24 08       	mov    %rax,0x8(%rsp)
  19:	48 8d 44 24 20       	lea    0x20(%rsp),%rax
  1e:	48 89 44 24 10       	mov    %rax,0x10(%rsp)
  23:	b8 10 00 00 00       	mov    $0x10,%eax
  28:	0f 05                	syscall 
  2a:*	89 c2                	mov    %eax,%edx		<-- trapping instruction
  2c:	3d 00 f0 ff ff       	cmp    $0xfffff000,%eax
  31:	77 1c                	ja     0x4f
  33:	48 8b 44 24 18       	mov    0x18(%rsp),%rax
  38:	64                   	fs
  39:	48                   	rex.W
  3a:	2b                   	.byte 0x2b
  3b:	04 25                	add    $0x25,%al
  3d:	28 00                	sub    %al,(%rax)
	...

Code starting with the faulting instruction
===========================================
   0:	89 c2                	mov    %eax,%edx
   2:	3d 00 f0 ff ff       	cmp    $0xfffff000,%eax
   7:	77 1c                	ja     0x25
   9:	48 8b 44 24 18       	mov    0x18(%rsp),%rax
   e:	64                   	fs
   f:	48                   	rex.W
  10:	2b                   	.byte 0x2b
  11:	04 25                	add    $0x25,%al
  13:	28 00                	sub    %al,(%rax)
	...
[  415.282007][T21255] RSP: 002b:00007f128e7ff5e0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[  415.293025][T21255] RAX: ffffffffffffffda RBX: 000055cecae83b00 RCX: 00007f12912f8c5b
[  415.303708][T21255] RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 000000000000000c
[  415.314228][T21255] RBP: 000000000000ae80 R08: 0000000000000000 R09: 0000000000000000
[  415.324787][T21255] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
[  415.335326][T21255] R13: 0000000000000001 R14: 00000000000003f8 R15: 0000000000000000
[  415.345809][T21255]  </TASK>
[  415.351386][T21255] ---[ end trace ]---



The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20240724/202407242159.893be500-oliver.sang@xxxxxxxxx



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https://github.com/intel/lkp-tests/wiki