On Thu, Apr 25, 2019 at 05:07:05PM -0700, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: 76c938fc Add linux-next specific files for 20190423 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=16863d28a00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=62738d35457c577d > dashboard link: https://syzkaller.appspot.com/bug?extid=f7e65445a40d3e0e4ebf > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1364a6d4a00000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17c25dc4a00000 > > Bisection is inconclusive: the first bad commit could be any of: > > 57bf67e7 KVM: lapic: Disable timer advancement if adaptive tuning goes > haywire > 39497d76 KVM: lapic: Track lapic timer advance per vCPU Well that was depressingly easy to reproduce. The per-vCPU commit is at fault, it fails to ensure the lapic is in kernel before dereferencing the associated pointer. Patch incoming... > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=17a32fc4a00000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+f7e65445a40d3e0e4ebf@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. > kasan: CONFIG_KASAN_INLINE enabled > kasan: GPF could be caused by NULL-ptr deref or user memory access > general protection fault: 0000 [#1] PREEMPT SMP KASAN > CPU: 0 PID: 7872 Comm: syz-executor233 Not tainted 5.1.0-rc6-next-20190423 > #29 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > RIP: 0010:vcpu_enter_guest+0xbcd/0x5fb0 arch/x86/kvm/x86.c:7895 > Code: 48 c1 ea 03 80 3c 02 00 0f 85 6f 48 00 00 49 8b 9f b0 03 00 00 48 b8 > 00 00 00 00 00 fc ff df 48 8d 7b 78 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 > 74 08 3c 03 0f 8e 39 48 00 00 8b 5b 78 31 ff 89 > RSP: 0018:ffff88808bd4fa00 EFLAGS: 00010006 > RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff810d1ec9 > RDX: 000000000000000f RSI: ffffffff810ceef2 RDI: 0000000000000078 > RBP: ffff88808bd4fb10 R08: ffff8880a912e580 R09: ffffed1015d05dd0 > R10: ffffed1015d05dcf R11: ffff8880ae82ee7b R12: ffff88808f3e006c > R13: 0000000000000001 R14: ffff88808f3e0070 R15: ffff88808f3e0040 > FS: 00007f7adb927700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007fa0427eb000 CR3: 00000000939e4000 CR4: 00000000001426f0 > Call Trace: > vcpu_run arch/x86/kvm/x86.c:8037 [inline] > kvm_arch_vcpu_ioctl_run+0x425/0x1750 arch/x86/kvm/x86.c:8245 > kvm_vcpu_ioctl+0x4dc/0xf90 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2684 > vfs_ioctl fs/ioctl.c:46 [inline] > file_ioctl fs/ioctl.c:509 [inline] > do_vfs_ioctl+0xd6e/0x1390 fs/ioctl.c:696 > ksys_ioctl+0xab/0xd0 fs/ioctl.c:713 > __do_sys_ioctl fs/ioctl.c:720 [inline] > __se_sys_ioctl fs/ioctl.c:718 [inline] > __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 > do_syscall_64+0x103/0x670 arch/x86/entry/common.c:298 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x446779 > Code: e8 5c b3 02 00 48 83 c4 18 c3 0f 1f 80 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 > 0f 83 0b 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007f7adb926db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > RAX: ffffffffffffffda RBX: 00000000006dbc48 RCX: 0000000000446779 > RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005 > RBP: 00000000006dbc40 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc4c > R13: 00007fff1cfa7c1f R14: 00007f7adb9279c0 R15: 20c49ba5e353f7cf > Modules linked in: > ---[ end trace da6276bd16a5f99d ]--- > RIP: 0010:vcpu_enter_guest+0xbcd/0x5fb0 arch/x86/kvm/x86.c:7895 > Code: 48 c1 ea 03 80 3c 02 00 0f 85 6f 48 00 00 49 8b 9f b0 03 00 00 48 b8 > 00 00 00 00 00 fc ff df 48 8d 7b 78 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 > 74 08 3c 03 0f 8e 39 48 00 00 8b 5b 78 31 ff 89 > RSP: 0018:ffff88808bd4fa00 EFLAGS: 00010006 > RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff810d1ec9 > RDX: 000000000000000f RSI: ffffffff810ceef2 RDI: 0000000000000078 > RBP: ffff88808bd4fb10 R08: ffff8880a912e580 R09: ffffed1015d05dd0 > R10: ffffed1015d05dcf R11: ffff8880ae82ee7b R12: ffff88808f3e006c > R13: 0000000000000001 R14: ffff88808f3e0070 R15: ffff88808f3e0040 > FS: 00007f7adb927700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007fa0427eb000 CR3: 00000000939e4000 CR4: 00000000001426f0 > > > --- > 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@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this bug report. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > For information about bisection process see: https://goo.gl/tpsmEJ#bisection > syzbot can test patches for this bug, for details see: > https://goo.gl/tpsmEJ#testing-patches
