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? > > > > > When early abort is occurred due to invalid ACPI information, Linux kernel > > terminates ACPI by calling acpi_terminate() function. > > The function calls acpi_ns_terminate() function to delete namespace data > > and ACPI operand cache (acpi_gbl_module_code_list). > > > > But the deletion code in acpi_ns_terminate() function is wrapped in > > ACPI_EXEC_APP definition, therefore the code is only executed when the > > definition exists. > > If the define doesn't exist, ACPI operand cache (acpi_gbl_module_code_list) is > > leaked, and stack dump is shown in kernel log. > > > > acpi_ns_terminate() actually shouldn't be invoked by Linux. > It's not fully functioning in Linux kernel environment. > > > This causes a security threat because the old kernel (<= 4.9) shows memory > > locations of kernel functions in stack dump, therefore kernel ASLR can be > > neutralized. > > > > To fix ACPI operand leak for enhancing security, I made a patch which removes > > the ACPI_EXEC_APP define in acpi_ns_terminate() function for executing the > > deletion code unconditionally. > > However acpi_gbl_module_code_list deletion shouldn't be dependent on ACPI_EXEC_APP. > So your change is acceptable. > > > > > I hope that this patch improves the security of Linux kernel. > > > > Thank you. > > > > Signed-off-by: Seunghun Han <kkamagui@xxxxxxxxx> > > --- > > Changes since v1: move position of variables to remove compile warning. > > > > drivers/acpi/acpica/nsutils.c | 23 +++++++++-------------- > > 1 file changed, 9 insertions(+), 14 deletions(-) > > > > diff --git a/drivers/acpi/acpica/nsutils.c b/drivers/acpi/acpica/nsutils.c > > index 691814d..943702d 100644 > > --- a/drivers/acpi/acpica/nsutils.c > > +++ b/drivers/acpi/acpica/nsutils.c > > @@ -594,25 +594,20 @@ struct acpi_namespace_node *acpi_ns_validate_handle(acpi_handle handle) > > void acpi_ns_terminate(void) > > { > > acpi_status status; > > + union acpi_operand_object *prev; > > + union acpi_operand_object *next; > > > > ACPI_FUNCTION_TRACE(ns_terminate); > > > > -#ifdef ACPI_EXEC_APP > > - { > > - union acpi_operand_object *prev; > > - union acpi_operand_object *next; > > + /* Delete any module-level code blocks */ > > > > - /* Delete any module-level code blocks */ > > - > > - next = acpi_gbl_module_code_list; > > - while (next) { > > - prev = next; > > - next = next->method.mutex; > > - prev->method.mutex = NULL; /* Clear the Mutex (cheated) field */ > > - acpi_ut_remove_reference(prev); > > - } > > + next = acpi_gbl_module_code_list; > > + while (next) { > > + prev = next; > > + next = next->method.mutex; > > + prev->method.mutex = NULL; /* Clear the Mutex (cheated) field */ > > + acpi_ut_remove_reference(prev); > > } > > -#endif > > Thus this looks OK to me. > > > > > /* > > * Free the entire namespace -- all nodes and all objects > > -- > > 2.1.4 I still would prefer it to go in via the upstream. 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
