linux-kernel - KASAN: out-of-bounds Read in kvm_arch_hardware

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Message-ID: <000000000000a0784a05a916495e@google.com>
Date:   Sat, 27 Jun 2020 13:01:13 -0700
From:   syzbot <syzbot+e0240f9c36530bda7130@...kaller.appspotmail.com>
To:     bp@...en8.de, hpa@...or.com, jmattson@...gle.com, joro@...tes.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        mingo@...hat.com, pbonzini@...hat.com,
        sean.j.christopherson@...el.com, syzkaller-bugs@...glegroups.com,
        tglx@...utronix.de, vkuznets@...hat.com, wanpengli@...cent.com,
        x86@...nel.org
Subject: KASAN: out-of-bounds Read in kvm_arch_hardware_setup

Hello,

syzbot found the following crash on:

HEAD commit:    7ae77150 Merge tag 'powerpc-5.8-1' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1654e385100000
kernel config:  https://syzkaller.appspot.com/x/.config?x=be4578b3f1083656
dashboard link: https://syzkaller.appspot.com/bug?extid=e0240f9c36530bda7130
compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15f3abc9100000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=131b7bb5100000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e0240f9c36530bda7130@...kaller.appspotmail.com

==================================================================
BUG: KASAN: out-of-bounds in kvm_cpu_cap_get arch/x86/kvm/cpuid.h:292 [inline]
BUG: KASAN: out-of-bounds in kvm_cpu_cap_has arch/x86/kvm/cpuid.h:297 [inline]
BUG: KASAN: out-of-bounds in kvm_init_msr_list arch/x86/kvm/x86.c:5362 [inline]
BUG: KASAN: out-of-bounds in kvm_arch_hardware_setup+0xb05/0xf40 arch/x86/kvm/x86.c:9802
Read of size 4 at addr ffffffff896c3134 by task syz-executor614/6786

CPU: 1 PID: 6786 Comm: syz-executor614 Not tainted 5.7.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1e9/0x30e lib/dump_stack.c:118
 print_address_description+0x66/0x5a0 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report+0x132/0x1d0 mm/kasan/report.c:530
 kvm_cpu_cap_get arch/x86/kvm/cpuid.h:292 [inline]
 kvm_cpu_cap_has arch/x86/kvm/cpuid.h:297 [inline]
 kvm_init_msr_list arch/x86/kvm/x86.c:5362 [inline]
 kvm_arch_hardware_setup+0xb05/0xf40 arch/x86/kvm/x86.c:9802
 </IRQ>

The buggy address belongs to the variable:
 kvm_cpu_caps+0x24/0x50

Memory state around the buggy address:
 ffffffff896c3000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffff896c3080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffffff896c3100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                        ^
 ffffffff896c3180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffff896c3200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@...glegroups.com.

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