Hi, > From: Seunghun Han [mailto:kkamagui@xxxxxxxxx] > Subject: Re: [PATCH v2] acpi: acpica: fix acpi operand cache leak > > Hello, Lv and Rafael. > > I checked that my patch was merged to ACPICA project. > Thank you for your notice. > > I added an analysis report which has the root cause of this problem below. > > 2017-02-27 11:45 GMT+09:00 Zheng, Lv <lv.zheng@xxxxxxxxx>: > > Hi, Rafael > > > >> From: linux-acpi-owner@xxxxxxxxxxxxxxx [mailto:linux-acpi-owner@xxxxxxxxxxxxxxx] On Behalf Of > Rafael J. > >> Wysocki > >> Subject: Re: [PATCH v2] acpi: acpica: fix acpi operand cache leak > >> > >> On Fri, Feb 24, 2017 at 11:37 PM, Seunghun Han <kkamagui@xxxxxxxxx> wrote: > >> > Hi, Rafael. > >> > > >> > I agree with you and I added my opinion below. > >> > > >> > 2017-02-25 1:50 GMT+09:00 Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>: > >> >> On Friday, February 24, 2017 09:56:21 PM Seunghun Han wrote: > >> >>> Hi, Rafeal. > >> >>> > >> >>> I added my opinion below. > >> >>> > >> >>> 2017-02-24 21:13 GMT+09:00 Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>: > >> >>> > On Friday, February 24, 2017 09:15:52 PM Seunghun Han wrote: > >> >>> >> Hi, Rafael. > >> >>> >> > >> >>> >> I added my opinion below. > >> >>> >> > >> >>> >> 2017-02-24 20:50 GMT+09:00 Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>: > >> >>> >> > On Friday, February 24, 2017 08:52:42 PM Seunghun Han wrote: > >> >>> >> >> Hi, Lv Zheng. > >> >>> >> >> > >> >>> >> >> I added my handcrafted ACPI table under your request, because > >> >>> >> >> "acpidump -c on" and "acpidump -c off" doesn't work. > >> >>> >> >> > >> >>> >> >> 2017-02-21 19:36 GMT+09:00 Seunghun Han <kkamagui@xxxxxxxxx>: > >> >>> >> >> > Hello, > >> >>> >> >> > > >> >>> >> >> > I attached the test results below, > >> >>> >> >> > > >> >>> >> >> > 2017-02-21 9:53 GMT+09:00 Rowafael J. Wysocki <rjw@xxxxxxxxxxxxx>: > >> >>> >> >> >> On Tuesday, February 21, 2017 12:33:08 AM Zheng, Lv wrote: > >> >>> >> >> >>> Hi, > >> >>> >> >> >>> > >> >>> >> >> >>> > From: linux-acpi-owner@xxxxxxxxxxxxxxx [mailto:linux-acpi-owner@xxxxxxxxxxxxxxx] On > >> Behalf Of Seunghun > >> >>> >> >> >>> > Han > >> >>> >> >> >>> > Subject: [PATCH v2] acpi: acpica: fix acpi operand cache leak > >> >>> >> >> >>> > > >> >>> >> >> >>> > I'm Seunghun Han, and I work for National Security Research Institute of > >> >>> >> >> >>> > South Korea. > >> >>> >> >> >>> > > >> >>> >> >> >>> > I have been doing a research on ACPI and making a handcrafted ACPI table > >> >>> >> >> >>> > for my research. > >> >>> >> >> >>> > Errors of handcrafted ACPI tables are handled well in Linux kernel while boot > >> >>> >> >> >>> > process, and Linux kernel goes well without critical problems. > >> >>> >> >> >>> > But I found some ACPI operand cache leaks in ACPI early abort cases. > >> >>> >> >> >>> > > >> >>> >> >> >>> > Boot log of ACPI operand cache leak is as follows: > >> >>> >> >> >>> > >[ 0.174332] ACPI: Added _OSI(Module Device) > >> >>> >> >> >>> > >[ 0.175504] ACPI: Added _OSI(Processor Device) > >> >>> >> >> >>> > >[ 0.176010] ACPI: Added _OSI(3.0 _SCP Extensions) > >> >>> >> >> >>> > >[ 0.177032] ACPI: Added _OSI(Processor Aggregator Device) > >> >>> >> >> >>> > >[ 0.178284] ACPI: SCI (IRQ16705) allocation failed > >> >>> >> >> >>> > >[ 0.179352] ACPI Exception: AE_NOT_ACQUIRED, Unable to install System Control > >> Interrupt handler > >> >>> >> >> >>> > (20160930/evevent-131) > >> >>> >> >> >>> > >[ 0.180008] ACPI: Unable to start the ACPI Interpreter > >> >>> >> >> >>> > >[ 0.181125] ACPI Error: Could not remove SCI handler (20160930/evmisc-281) > >> >>> >> >> >>> > >[ 0.184068] kmem_cache_destroy Acpi-Operand: Slab cache still has objects > >> >>> >> >> >>> > >[ 0.185358] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.10.0-rc3 #2 > >> >>> >> >> >>> > >[ 0.186820] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox > >> 12/01/2006 > >> >>> >> >> >>> > >[ 0.188000] Call Trace: > >> >>> >> >> >>> > >[ 0.188000] ? dump_stack+0x5c/0x7d > >> >>> >> >> >>> > >[ 0.188000] ? kmem_cache_destroy+0x224/0x230 > >> >>> >> >> >>> > >[ 0.188000] ? acpi_sleep_proc_init+0x22/0x22 > >> >>> >> >> >>> > >[ 0.188000] ? acpi_os_delete_cache+0xa/0xd > >> >>> >> >> >>> > >[ 0.188000] ? acpi_ut_delete_caches+0x3f/0x7b > >> >>> >> >> >>> > >[ 0.188000] ? acpi_terminate+0x5/0xf > >> >>> >> >> >>> > >[ 0.188000] ? acpi_init+0x288/0x32e > >> >>> >> >> >>> > >[ 0.188000] ? __class_create+0x4c/0x80 > >> >>> >> >> >>> > >[ 0.188000] ? video_setup+0x7a/0x7a > >> >>> >> >> >>> > >[ 0.188000] ? do_one_initcall+0x4e/0x1b0 > >> >>> >> >> >>> > >[ 0.188000] ? kernel_init_freeable+0x194/0x21a > >> >>> >> >> >>> > >[ 0.188000] ? rest_init+0x80/0x80 > >> >>> >> >> >>> > >[ 0.188000] ? kernel_init+0xa/0x100 > >> >>> >> >> >>> > >[ 0.188000] ? ret_from_fork+0x25/0x30 > >> >>> >> >> >>> > >> >>> >> >> >>> I'm more interested in the way of triggering AE_NOT_ACQUIRED error. > >> >>> >> >> >>> So could you send us the handcrafted ACPI table or both the "acpidump -c on" and > >> "acpidump -c off" output? > >> >>> >> >> > >> >>> >> >> I modified FACP, FACS, APIC table in VirtualBox for Linux. > >> >>> >> >> Here are raw dumps of table. > >> >>> >> > > >> >>> >> > So, excuse me, but what's the security issue here? > >> >>> >> > > >> >>> >> > You hacked your ACPI tables into pieces which requires root privileges anyway. > >> >>> >> > > >> >>> >> > Thanks, > >> >>> >> > Rafael > >> >>> >> > > >> >>> >> > >> >>> >> As you mentioned earlier, I hacked my ACPI table for research, so it seems that > >> >>> >> it is not a security issue. > >> >>> >> > >> >>> >> But, if new mainboard are released and they have a vendor-specific ACPI table > >> >>> >> which has invalid data, the old version of kernel (<=4.9) will possibly expose > >> >>> >> kernel address and KASLR will be neutralized unintentionally. > >> >>> > > >> >>> > But that would mean a basically non-functional system, so I'm not sure how > >> >>> > anyone can actually take advantage of the "KASLR neutralization". > >> >>> > >> >>> I think an attacker can take advantage of the "KASLR neutralization". As you > >> >>> know, KASLR is good technology to protect kernel from kernel exploits. > >> >>> > >> >>> If the kernel has vulnerabilities, the attacker can make exploit using them. > >> >>> But, the exploit usually needs gadgets (small code), therefore the attacker > >> >>> should know where the gadgets are in kernel. If the KASLR is working in kernel, > >> >>> the attacker should find the actual kernel address, and he can get kernel > >> >>> address information from kernel warning. > >> >> > >> >> If the system basically doesn't work, that information isn't particularly useful. > >> >> > >> >>> >> I know the vendors collaborate with Linux kernel developers, but the problem > >> >>> >> can still occur. > >> >>> >> > >> >>> >> Hardware vendors release so many kinds of mainboard in a year, and the major > >> >>> >> Linux distros (Ubuntu, Fedora, etc.) will have 4.8 kernel for a long time. > >> >>> >> > >> >>> >> For this reason, I think this issue has a security aspect. > >> >>> > > >> >>> > Well, not quite IMO. > >> >>> > > >> >>> > If the system needs ACPI tables and the kernel cannot use them, it just won't > >> >>> > work no matter what. > >> >>> > > >> >>> > Thanks, > >> >>> > Rafael > >> >>> > > >> >>> Yes, you are right. But, Linux kernel has well-defined exception handlers, so > >> >>> some systems may work fine like my test machine. Moreover the users may not > >> >>> recognize what the problem is, and I think that they will use the system in > >> >>> insecure status for a long time. > >> >> > >> >> A virtual box or a guest can run without ACPI tables. A bare metal system > >> >> where ACPI tables are necessary will be more-or-less unusable if the kernel > >> >> cannot use them (it won't be able to detect interrupt controllers and the PCI > >> >> host bridge just for starters). > >> >> > >> >> Running a guest with totally broken ACPI tables requires root privileges on the > >> >> host. Running a bare metal system with totally broken ACPI tables (which seems > >> >> to be your basic concern) may be a good research project, but nobody will do > >> >> that in practice. And everybody who tries that will notice what's going on. > >> >> > >> >> Yes, you found a bug, but I still am not convinced about how this is security-related. > >> > > >> > I totally agree with you that this case is not in practice now. > >> > I just started researching on ACPI, and I don't have enough ideas to occur > >> > a security problem using a bug. I just think that it has a little possibility > >> > which is security-related. > >> > > >> > Thank you so much for your guides. > >> > It helps me a lot to change my research direction. > >> > > >> > So, could my patch be merged in next kernel (4.11 rc-1)? or do I need to do > >> > something for it? > >> > Please let me know. > >> > >> Generally, ACPICA patches (and this is one of them) have to go in via > >> the upstream ACPICA project maintained by Bob Moore and Lv. Please > >> see MAINTAINERS for pointers to the mailing list etc. > >> > >> Lv, can you please advise on the next steps? > > > > I already gave my advices. > > The fix was OK to me and I back ported it to ACPICA: > > https://github.com/acpica/acpica/pull/206 > > However it fixes a code path that in theory shouldn't be invoked in Linux kernel. > > But anyway it was merged and you will see it in the next ACPICA release. > > > > I asked Han for the handcrafted ACPI table. > > And obtained that: > > ACPI: FACP 0x00000000DFFF00F0 0000F4 (v04 VBOX VBOXFACP 00000001 ASL 00000061) > > 0x0000: 46 41 43 50 F4 00 00 00 04 60 56 42 4F 58 20 20 > > 0x0010: 56 42 4F 58 46 41 43 50 01 00 00 00 41 53 4C 20 > > 0x0020: 61 00 00 00 00 02 FF DF 80 04 FF DF 41 41 41 41 > > 0x0030: 2E 44 00 00 A1 A0 00 00 00 40 00 00 00 00 00 00 > > 0x0040: 04 40 00 00 00 00 00 00 00 00 00 00 08 40 00 00 > > 0x0050: 20 40 00 00 00 00 00 00 04 02 00 04 02 00 00 00 > > 0x0060: 65 00 E9 03 00 00 00 00 00 00 00 00 00 03 00 00 > > 0x0070: 41 05 00 00 01 08 00 01 50 40 00 00 00 00 00 00 > > 0x0080: 10 00 00 00 00 02 FF DF 00 00 00 00 80 04 FF DF > > 0x0090: 00 00 00 00 01 20 00 02 00 40 00 00 00 00 00 00 > > 0x00A0: 00 00 00 00 00 00 00 00 00 00 00 00 01 10 00 02 > > 0x00B0: 04 40 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > 0x00C0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > 0x00D0: 01 20 00 03 08 40 00 00 00 00 00 00 01 10 00 01 > > 0x00E0: 20 40 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > 0x00F0: 00 00 00 00 > > > > ACPI: FACS 0x00000000DFFF0200 000040 > > 0x0000: 46 41 43 53 40 00 00 00 00 00 00 00 00 00 00 00 > > 0x0010: 00 00 00 00 00 00 00 00 00 41 41 41 41 41 41 41 > > 0x0020: 01 00 00 00 00 00 00 00 00 41 00 00 00 00 00 00 > > 0x0030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > > ACPI: APIC 0x00000000DFFF0240 00006C (v02 VBOX VBOXAPIC 00000001 ASL 00000061) > > 0x0000: 41 50 49 43 6C 00 00 00 02 21 56 42 4F 58 20 20 > > 0x0010: 56 42 4F 58 41 50 49 43 01 00 00 00 41 53 4C 20 > > 0x0020: 61 00 00 00 00 00 E0 FE 01 00 00 00 02 0A 00 00 > > 0x0030: 02 00 00 00 00 00 02 0A 00 09 09 00 00 00 0D 00 > > 0x0040: 00 08 00 00 01 00 41 41 41 41 41 41 41 41 41 00 > > 0x0050: 00 08 02 02 01 00 00 00 00 08 03 03 01 00 00 00 > > 0x0060: 01 0C 04 00 00 00 C0 FE 00 00 00 00 > > > > Where there is still no AML tables and the failure in the patch description seems to be related to > the AML tables. > > So I'm still not aware of what the "handcrafted tables" meant to us and what the problem was. > > Actually, I did not change DSDT and SSDT. I changed only FACP, FACS and APIC for > my handcrafted ACPI table. > > I have analyzed the root cause of the problem, and I have found that my > handcrafted ACPI table has too big SCI IRQ (like 16705). > So, acpi_os_install_interrupt_handler() which is called by > acpi_enable_subsystem() > was failed and returned AE_NOT_ACQUIRED (0x14) with "ACPI: SCI (IRQ16705) > allocation failed" log. Thanks for the explanation. There doesn't seem to be any required additional fix for such a wrong sci irq #. Which can release me from the triggered error now. :) > > Because of error code, acpi_bus_init(), the caller of acpi_enable_subsystem(), > showed "Unable to start the ACPI Interpreter" and called acpi_terminate() for > exception handling. After calling acpi_terminate(), as you know, cache leak > occurred. > This means that error of acpi_load_tables(), acpi_initialize_objects(), > acpi_bus_init_irq() and acpi_install_notify_handler() which are called by > acpi_bus_init() can cause cache leak. > > If you want to see this error handling sequence, I suggest you that you change > the code of acpi_os_install_interrupt_handler() to return AE_NOT_ACQUIRED > immediately. Then, you can see the error handling sequence without my > handcrafted > ACPI table. You can always harden the code with acceptable improvements. Feel free to continue your contribution. > > I you want additional information about this, please let me know. Sure. Thanks Lv > > Best regards. > > > > > Thanks and best regards > > Lv > > > >> > >> Thanks, > >> Rafael > >> -- > >> To unsubscribe from this list: send the line "unsubscribe linux-acpi" in > >> the body of a message to majordomo@xxxxxxxxxxxxxxx > >> More majordomo info at http://vger.kernel.org/majordomo-info.html ��.n��������+%������w��{.n�����{�����ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
