| Message ID | 20170113175904.GA23569@potion (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Jan 13, 2017 at 6:59 PM, Radim Krčmář <rkrcmar@redhat.com> wrote: > 2017-01-02 11:23+0100, Dmitry Vyukov: >> Hello, >> >> I've got the following warning while running syzkaller fuzzer: >> >> WARNING: CPU: 2 PID: 13257 at arch/x86/kvm/vmx.c:8633 >> vmx_handle_exit+0x262b/0x38b0 arch/x86/kvm/vmx.c:8633 >> vmx: unexpected exit reason 0xb >> CPU: 2 PID: 13257 Comm: syz-executor7 Not tainted 4.10.0-rc1+ #118 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 >> Call Trace: >> __dump_stack lib/dump_stack.c:15 [inline] >> dump_stack+0x292/0x3a2 lib/dump_stack.c:51 >> panic+0x1cb/0x3a9 kernel/panic.c:179 >> __warn+0x1c4/0x1e0 kernel/panic.c:539 >> warn_slowpath_fmt+0xc5/0x100 kernel/panic.c:562 >> vmx_handle_exit+0x262b/0x38b0 arch/x86/kvm/vmx.c:8633 >> vcpu_enter_guest arch/x86/kvm/x86.c:6884 [inline] >> vcpu_run arch/x86/kvm/x86.c:6943 [inline] >> kvm_arch_vcpu_ioctl_run+0xf3d/0x45f0 arch/x86/kvm/x86.c:7101 >> kvm_vcpu_ioctl+0x673/0x1120 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2569 >> vfs_ioctl fs/ioctl.c:43 [inline] >> do_vfs_ioctl+0x1bf/0x1780 fs/ioctl.c:683 >> SYSC_ioctl fs/ioctl.c:698 [inline] >> SyS_ioctl+0x8f/0xc0 fs/ioctl.c:689 >> entry_SYSCALL_64_fastpath+0x1f/0xc2 >> RIP: 0033:0x4438a9 >> RSP: 002b:00007f935aa2fb58 EFLAGS: 00000286 ORIG_RAX: 0000000000000010 >> RAX: ffffffffffffffda RBX: 0000000000000015 RCX: 00000000004438a9 >> RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000015 >> RBP: 00000000006ddb30 R08: 0000000000000000 R09: 0000000000000000 >> R10: 0000000000000000 R11: 0000000000000286 R12: 0000000000700000 >> R13: 0000000000000006 R14: 0000000000000015 R15: 0000000020014000 >> Dumping ftrace buffer: >> (ftrace buffer empty) >> Kernel Offset: disabled >> >> Exit reason 0xb is GETSEC instruction. This does not look harmful as >> it is handled as #UD. But I think we should print a single line >> message regarding non-emulated instruction as in other cases, just to >> not scare cloud admins and to make syzkaller ignore it. >> >> FTR, a raw reproducer is here: >> https://gist.githubusercontent.com/dvyukov/c762f6ea04ebbba49cdee0a6caca31b4/raw/f21deb04cdc70ae74100c12447d71bb0cd2025c7/gistfile1.txt > > I can't reproduce -- maybe a nested bug, which will take a while to > figure out. Still, host dump at that point is useless, so the change > makes sense. > > A guest dump would be useful (e.g. I think that GETSEC should not exit Thanks! I had to disable dump_vmcs locally because it constantly produces tons of output even when no bugs happen. If you really-really need it, I can enable dump_vmcs and re-reproduce the bug. > if guest CR4.SMX is disabled), but just giving the error is about as > good and we want something short and rate-limited if the message can be > trigerred by a guest in production ... > ---8<--- > We never needed the call trace and we better rate-limit if it can be > triggered by a guest. > > Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> > --- > arch/x86/kvm/vmx.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index a236decb81e4..7cd606daa01e 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -8595,7 +8595,8 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu) > && kvm_vmx_exit_handlers[exit_reason]) > return kvm_vmx_exit_handlers[exit_reason](vcpu); > else { > - WARN_ONCE(1, "vmx: unexpected exit reason 0x%x\n", exit_reason); > + vcpu_unimpl(vcpu, "vmx: unexpected exit reason 0x%x\n", > + exit_reason); > kvm_queue_exception(vcpu, UD_VECTOR); > return 1; > } > -- > 2.11.0 > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Sun, Jan 15, 2017 at 8:18 PM, Dmitry Vyukov <dvyukov@google.com> wrote: >> 2017-01-02 11:23+0100, Dmitry Vyukov: >>> Hello, >>> >>> I've got the following warning while running syzkaller fuzzer: >>> >>> WARNING: CPU: 2 PID: 13257 at arch/x86/kvm/vmx.c:8633 >>> vmx_handle_exit+0x262b/0x38b0 arch/x86/kvm/vmx.c:8633 >>> vmx: unexpected exit reason 0xb >>> CPU: 2 PID: 13257 Comm: syz-executor7 Not tainted 4.10.0-rc1+ #118 >>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 >>> Call Trace: >>> __dump_stack lib/dump_stack.c:15 [inline] >>> dump_stack+0x292/0x3a2 lib/dump_stack.c:51 >>> panic+0x1cb/0x3a9 kernel/panic.c:179 >>> __warn+0x1c4/0x1e0 kernel/panic.c:539 >>> warn_slowpath_fmt+0xc5/0x100 kernel/panic.c:562 >>> vmx_handle_exit+0x262b/0x38b0 arch/x86/kvm/vmx.c:8633 >>> vcpu_enter_guest arch/x86/kvm/x86.c:6884 [inline] >>> vcpu_run arch/x86/kvm/x86.c:6943 [inline] >>> kvm_arch_vcpu_ioctl_run+0xf3d/0x45f0 arch/x86/kvm/x86.c:7101 >>> kvm_vcpu_ioctl+0x673/0x1120 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2569 >>> vfs_ioctl fs/ioctl.c:43 [inline] >>> do_vfs_ioctl+0x1bf/0x1780 fs/ioctl.c:683 >>> SYSC_ioctl fs/ioctl.c:698 [inline] >>> SyS_ioctl+0x8f/0xc0 fs/ioctl.c:689 >>> entry_SYSCALL_64_fastpath+0x1f/0xc2 >>> RIP: 0033:0x4438a9 >>> RSP: 002b:00007f935aa2fb58 EFLAGS: 00000286 ORIG_RAX: 0000000000000010 >>> RAX: ffffffffffffffda RBX: 0000000000000015 RCX: 00000000004438a9 >>> RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000015 >>> RBP: 00000000006ddb30 R08: 0000000000000000 R09: 0000000000000000 >>> R10: 0000000000000000 R11: 0000000000000286 R12: 0000000000700000 >>> R13: 0000000000000006 R14: 0000000000000015 R15: 0000000020014000 >>> Dumping ftrace buffer: >>> (ftrace buffer empty) >>> Kernel Offset: disabled >>> >>> Exit reason 0xb is GETSEC instruction. This does not look harmful as >>> it is handled as #UD. But I think we should print a single line >>> message regarding non-emulated instruction as in other cases, just to >>> not scare cloud admins and to make syzkaller ignore it. >>> >>> FTR, a raw reproducer is here: >>> https://gist.githubusercontent.com/dvyukov/c762f6ea04ebbba49cdee0a6caca31b4/raw/f21deb04cdc70ae74100c12447d71bb0cd2025c7/gistfile1.txt >> >> I can't reproduce -- maybe a nested bug, which will take a while to >> figure out. Still, host dump at that point is useless, so the change >> makes sense. >> >> A guest dump would be useful (e.g. I think that GETSEC should not exit > > Thanks! > > I had to disable dump_vmcs locally because it constantly produces tons > of output even when no bugs happen. > If you really-really need it, I can enable dump_vmcs and re-reproduce the bug. > > >> if guest CR4.SMX is disabled), but just giving the error is about as >> good and we want something short and rate-limited if the message can be >> trigerred by a guest in production ... >> ---8<--- >> We never needed the call trace and we better rate-limit if it can be >> triggered by a guest. >> >> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> >> --- >> arch/x86/kvm/vmx.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >> index a236decb81e4..7cd606daa01e 100644 >> --- a/arch/x86/kvm/vmx.c >> +++ b/arch/x86/kvm/vmx.c >> @@ -8595,7 +8595,8 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu) >> && kvm_vmx_exit_handlers[exit_reason]) >> return kvm_vmx_exit_handlers[exit_reason](vcpu); >> else { >> - WARN_ONCE(1, "vmx: unexpected exit reason 0x%x\n", exit_reason); >> + vcpu_unimpl(vcpu, "vmx: unexpected exit reason 0x%x\n", >> + exit_reason); >> kvm_queue_exception(vcpu, UD_VECTOR); >> return 1; >> } >> -- >> 2.11.0 >> Was this ever merged? Still happens for me.
2017-03-10 19:56+0100, Dmitry Vyukov: > On Sun, Jan 15, 2017 at 8:18 PM, Dmitry Vyukov <dvyukov@google.com> wrote: > >> 2017-01-02 11:23+0100, Dmitry Vyukov: > >>> Hello, > >>> > >>> I've got the following warning while running syzkaller fuzzer: > >>> > >>> WARNING: CPU: 2 PID: 13257 at arch/x86/kvm/vmx.c:8633 > >>> vmx_handle_exit+0x262b/0x38b0 arch/x86/kvm/vmx.c:8633 > >>> vmx: unexpected exit reason 0xb > >>> CPU: 2 PID: 13257 Comm: syz-executor7 Not tainted 4.10.0-rc1+ #118 > >>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 > >>> Call Trace: > >>> __dump_stack lib/dump_stack.c:15 [inline] > >>> dump_stack+0x292/0x3a2 lib/dump_stack.c:51 > >>> panic+0x1cb/0x3a9 kernel/panic.c:179 > >>> __warn+0x1c4/0x1e0 kernel/panic.c:539 > >>> warn_slowpath_fmt+0xc5/0x100 kernel/panic.c:562 > >>> vmx_handle_exit+0x262b/0x38b0 arch/x86/kvm/vmx.c:8633 > >>> vcpu_enter_guest arch/x86/kvm/x86.c:6884 [inline] > >>> vcpu_run arch/x86/kvm/x86.c:6943 [inline] > >>> kvm_arch_vcpu_ioctl_run+0xf3d/0x45f0 arch/x86/kvm/x86.c:7101 > >>> kvm_vcpu_ioctl+0x673/0x1120 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2569 > >>> vfs_ioctl fs/ioctl.c:43 [inline] > >>> do_vfs_ioctl+0x1bf/0x1780 fs/ioctl.c:683 > >>> SYSC_ioctl fs/ioctl.c:698 [inline] > >>> SyS_ioctl+0x8f/0xc0 fs/ioctl.c:689 > >>> entry_SYSCALL_64_fastpath+0x1f/0xc2 > >>> RIP: 0033:0x4438a9 > >>> RSP: 002b:00007f935aa2fb58 EFLAGS: 00000286 ORIG_RAX: 0000000000000010 > >>> RAX: ffffffffffffffda RBX: 0000000000000015 RCX: 00000000004438a9 > >>> RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000015 > >>> RBP: 00000000006ddb30 R08: 0000000000000000 R09: 0000000000000000 > >>> R10: 0000000000000000 R11: 0000000000000286 R12: 0000000000700000 > >>> R13: 0000000000000006 R14: 0000000000000015 R15: 0000000020014000 > >>> Dumping ftrace buffer: > >>> (ftrace buffer empty) > >>> Kernel Offset: disabled > >>> > >>> Exit reason 0xb is GETSEC instruction. This does not look harmful as > >>> it is handled as #UD. But I think we should print a single line > >>> message regarding non-emulated instruction as in other cases, just to > >>> not scare cloud admins and to make syzkaller ignore it. > >>> > >>> FTR, a raw reproducer is here: > >>> https://gist.githubusercontent.com/dvyukov/c762f6ea04ebbba49cdee0a6caca31b4/raw/f21deb04cdc70ae74100c12447d71bb0cd2025c7/gistfile1.txt > >> > >> I can't reproduce -- maybe a nested bug, which will take a while to > >> figure out. Still, host dump at that point is useless, so the change > >> makes sense. > >> > >> A guest dump would be useful (e.g. I think that GETSEC should not exit > > > > Thanks! > > > > I had to disable dump_vmcs locally because it constantly produces tons > > of output even when no bugs happen. > > If you really-really need it, I can enable dump_vmcs and re-reproduce the bug. > > > > > >> if guest CR4.SMX is disabled), but just giving the error is about as > >> good and we want something short and rate-limited if the message can be > >> trigerred by a guest in production ... > >> ---8<--- > >> We never needed the call trace and we better rate-limit if it can be > >> triggered by a guest. > >> > >> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> > >> --- > >> arch/x86/kvm/vmx.c | 3 ++- > >> 1 file changed, 2 insertions(+), 1 deletion(-) > >> > >> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > >> index a236decb81e4..7cd606daa01e 100644 > >> --- a/arch/x86/kvm/vmx.c > >> +++ b/arch/x86/kvm/vmx.c > >> @@ -8595,7 +8595,8 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu) > >> && kvm_vmx_exit_handlers[exit_reason]) > >> return kvm_vmx_exit_handlers[exit_reason](vcpu); > >> else { > >> - WARN_ONCE(1, "vmx: unexpected exit reason 0x%x\n", exit_reason); > >> + vcpu_unimpl(vcpu, "vmx: unexpected exit reason 0x%x\n", > >> + exit_reason); > >> kvm_queue_exception(vcpu, UD_VECTOR); > >> return 1; > >> } > >> -- > >> 2.11.0 > >> > > Was this ever merged? Still happens for me. No, it was forgotten ... queued now, Thanks
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index a236decb81e4..7cd606daa01e 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -8595,7 +8595,8 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu) && kvm_vmx_exit_handlers[exit_reason]) return kvm_vmx_exit_handlers[exit_reason](vcpu); else { - WARN_ONCE(1, "vmx: unexpected exit reason 0x%x\n", exit_reason); + vcpu_unimpl(vcpu, "vmx: unexpected exit reason 0x%x\n", + exit_reason); kvm_queue_exception(vcpu, UD_VECTOR); return 1; }