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. 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. I you want additional information about this, please let me know. 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 -- 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