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 > > -- > 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
