On Fri, 26 Feb 2021 at 15:01, syzbot syzbot+6987f3b2dbd9eda95f12@syzkaller.appspotmail.com wrote:

Hello,

syzbot found the following issue on:

HEAD commit: a99163e9 Merge tag 'devicetree-for-5.12' of git://git.kern.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=12d72682d00000 kernel config: https://syzkaller.appspot.com/x/.config?x=7a875029a795d230 dashboard link: https://syzkaller.appspot.com/bug?extid=6987f3b2dbd9eda95f12 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12faef12d00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=163342ccd00000

The issue was bisected to:

commit 8f014550dfb114cc7f42a517d20d2cf887a0b771 Author: Vitaly Kuznetsov vkuznets@redhat.com Date: Tue Jan 26 13:48:14 2021 +0000

KVM: x86: hyper-v: Make Hyper-V emulation enablement conditional

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=10df16a8d00000 final oops: https://syzkaller.appspot.com/x/report.txt?x=12df16a8d00000 console output: https://syzkaller.appspot.com/x/log.txt?x=14df16a8d00000

IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+6987f3b2dbd9eda95f12@syzkaller.appspotmail.com Fixes: 8f014550dfb1 ("KVM: x86: hyper-v: Make Hyper-V emulation enablement conditional")

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. general protection fault, probably for non-canonical address 0xdffffc0000000028: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000140-0x0000000000000147] CPU: 1 PID: 8370 Comm: syz-executor859 Not tainted 5.11.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:synic_get arch/x86/kvm/hyperv.c:165 [inline] RIP: 0010:kvm_hv_set_sint_gsi arch/x86/kvm/hyperv.c:475 [inline] RIP: 0010:kvm_hv_irq_routing_update+0x230/0x460 arch/x86/kvm/hyperv.c:498 Code: 80 19 00 00 48 89 f8 48 c1 e8 03 80 3c 28 00 0f 85 ff 01 00 00 4d 8b ad 80 19 00 00 49 8d bd 40 01 00 00 48 89 f8 48 c1 e8 03 <0f> b6 04 28 84 c0 74 06 0f 8e d2 01 00 00 45 0f b6 bd 40 01 00 00 RSP: 0018:ffffc90001b3fac0 EFLAGS: 00010206 RAX: 0000000000000028 RBX: ffff888012df5900 RCX: 0000000000000000 RDX: ffff888022193780 RSI: ffffffff81174d43 RDI: 0000000000000140 RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffc900018819eb R10: ffffffff81170f3e R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000001 FS: 0000000000a73300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000557e8c876888 CR3: 0000000013c0b000 CR4: 00000000001526e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: kvm_set_irq_routing+0x69b/0x940 arch/x86/kvm/../../../virt/kvm/irqchip.c:223 kvm_vm_ioctl+0x12d0/0x2800 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3959 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x43ef29 Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffe391eb808 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000400488 RCX: 000000000043ef29 RDX: 0000000020000140 RSI: 000000004008ae6a RDI: 0000000000000004 RBP: 0000000000402f10 R08: 0000000000400488 R09: 0000000000400488 R10: 0000000000400488 R11: 0000000000000246 R12: 0000000000402fa0 R13: 0000000000000000 R14: 00000000004ac018 R15: 0000000000400488 Modules linked in: ---[ end trace 2aa75ec1dd148710 ]--- RIP: 0010:synic_get arch/x86/kvm/hyperv.c:165 [inline]

Missing check to_hv_vcpu(vcpu) in synic_get(), I will fix it.

RIP: 0010:kvm_hv_set_sint_gsi arch/x86/kvm/hyperv.c:475 [inline] RIP: 0010:kvm_hv_irq_routing_update+0x230/0x460 arch/x86/kvm/hyperv.c:498 Code: 80 19 00 00 48 89 f8 48 c1 e8 03 80 3c 28 00 0f 85 ff 01 00 00 4d 8b ad 80 19 00 00 49 8d bd 40 01 00 00 48 89 f8 48 c1 e8 03 <0f> b6 04 28 84 c0 74 06 0f 8e d2 01 00 00 45 0f b6 bd 40 01 00 00 RSP: 0018:ffffc90001b3fac0 EFLAGS: 00010206 RAX: 0000000000000028 RBX: ffff888012df5900 RCX: 0000000000000000 RDX: ffff888022193780 RSI: ffffffff81174d43 RDI: 0000000000000140 RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffc900018819eb R10: ffffffff81170f3e R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000001 FS: 0000000000a73300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000557e8c876888 CR3: 0000000013c0b000 CR4: 00000000001526e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

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