syzbot


UBSAN: shift-out-of-bounds in kvm_vcpu_after_set_cpuid

Status: fixed on 2021/03/10 01:48
Reported-by: syzbot+e87846c48bf72bc85311@syzkaller.appspotmail.com
Fix commit: 2f80d502d627 KVM: x86: fix shift out of bounds reported by UBSAN
First crash: 714d, last: 714d

Sample crash report:
================================================================================
UBSAN: shift-out-of-bounds in arch/x86/kvm/mmu.h:52:16
shift exponent 64 is too large for 64-bit type 'long long unsigned int'
CPU: 1 PID: 11156 Comm: syz-executor.1 Not tainted 5.10.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:120
 ubsan_epilogue+0xb/0x5a lib/ubsan.c:148
 __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:395
 rsvd_bits arch/x86/kvm/mmu.h:52 [inline]
 kvm_vcpu_after_set_cpuid.cold+0x35/0x3a arch/x86/kvm/cpuid.c:181
 kvm_vcpu_ioctl_set_cpuid+0x28e/0x970 arch/x86/kvm/cpuid.c:273
 kvm_arch_vcpu_ioctl+0x1091/0x2d70 arch/x86/kvm/x86.c:4699
 kvm_vcpu_ioctl+0x7b9/0xdb0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3386
 kvm_vcpu_compat_ioctl+0x1a2/0x340 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3430
 __do_compat_sys_ioctl+0x1d3/0x230 fs/ioctl.c:842
 do_syscall_32_irqs_on arch/x86/entry/common.c:78 [inline]
 __do_fast_syscall_32+0x56/0x80 arch/x86/entry/common.c:137
 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:160
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
RIP: 0023:0xf7fe8549
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000f55e20cc EFLAGS: 00000296 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 000000004008ae8a
RDX: 00000000200000c0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
================================================================================

Crashes (2):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-386 2020/12/16 22:38 upstream 5e60366d56c6 04201c06 .config log report info
ci-upstream-kasan-gce-386 2020/12/16 18:04 upstream 5e60366d56c6 04201c06 .config log report info
* Struck through repros no longer work on HEAD.