97f3c0a4b0
I found an ACPI cache leak in ACPI early termination and boot continuing case. When early termination occurs due to malicious ACPI table, Linux kernel terminates ACPI function and continues to boot process. While kernel terminates ACPI function, kmem_cache_destroy() reports Acpi-Operand cache leak. Boot log of ACPI operand cache leak is as follows: >[ 0.464168] ACPI: Added _OSI(Module Device) >[ 0.467022] ACPI: Added _OSI(Processor Device) >[ 0.469376] ACPI: Added _OSI(3.0 _SCP Extensions) >[ 0.471647] ACPI: Added _OSI(Processor Aggregator Device) >[ 0.477997] ACPI Error: Null stack entry at ffff880215c0aad8 (20170303/exresop-174) >[ 0.482706] ACPI Exception: AE_AML_INTERNAL, While resolving operands for [opcode_name unavailable] (20170303/dswexec-461) >[ 0.487503] ACPI Error: Method parse/execution failed [\DBG] (Node ffff88021710ab40), AE_AML_INTERNAL (20170303/psparse-543) >[ 0.492136] ACPI Error: Method parse/execution failed [\_SB._INI] (Node ffff88021710a618), AE_AML_INTERNAL (20170303/psparse-543) >[ 0.497683] ACPI: Interpreter enabled >[ 0.499385] ACPI: (supports S0) >[ 0.501151] ACPI: Using IOAPIC for interrupt routing >[ 0.503342] ACPI Error: Null stack entry at ffff880215c0aad8 (20170303/exresop-174) >[ 0.506522] ACPI Exception: AE_AML_INTERNAL, While resolving operands for [opcode_name unavailable] (20170303/dswexec-461) >[ 0.510463] ACPI Error: Method parse/execution failed [\DBG] (Node ffff88021710ab40), AE_AML_INTERNAL (20170303/psparse-543) >[ 0.514477] ACPI Error: Method parse/execution failed [\_PIC] (Node ffff88021710ab18), AE_AML_INTERNAL (20170303/psparse-543) >[ 0.518867] ACPI Exception: AE_AML_INTERNAL, Evaluating _PIC (20170303/bus-991) >[ 0.522384] kmem_cache_destroy Acpi-Operand: Slab cache still has objects >[ 0.524597] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.12.0-rc5 #26 >[ 0.526795] Hardware name: innotek gmb_h virtual_box/virtual_box, BIOS virtual_box 12/01/2006 >[ 0.529668] Call Trace: >[ 0.530811] ? dump_stack+0x5c/0x81 >[ 0.532240] ? kmem_cache_destroy+0x1aa/0x1c0 >[ 0.533905] ? acpi_os_delete_cache+0xa/0x10 >[ 0.535497] ? acpi_ut_delete_caches+0x3f/0x7b >[ 0.537237] ? acpi_terminate+0xa/0x14 >[ 0.538701] ? acpi_init+0x2af/0x34f >[ 0.540008] ? acpi_sleep_proc_init+0x27/0x27 >[ 0.541593] ? do_one_initcall+0x4e/0x1a0 >[ 0.543008] ? kernel_init_freeable+0x19e/0x21f >[ 0.546202] ? rest_init+0x80/0x80 >[ 0.547513] ? kernel_init+0xa/0x100 >[ 0.548817] ? ret_from_fork+0x25/0x30 >[ 0.550587] vgaarb: loaded >[ 0.551716] EDAC MC: Ver: 3.0.0 >[ 0.553744] PCI: Probing PCI hardware >[ 0.555038] PCI host bridge to bus 0000:00 > ... Continue to boot and log is omitted ... I analyzed this memory leak in detail and found acpi_ns_evaluate() function only removes Info->return_object in AE_CTRL_RETURN_VALUE case. But, when errors occur, the status value is not AE_CTRL_RETURN_VALUE, and Info->return_object is also not null. Therefore, this causes acpi operand memory leak. This cache leak causes a security threat because an old kernel (<= 4.9) shows memory locations of kernel functions in stack dump. Some malicious users could use this information to neutralize kernel ASLR. I made a patch to fix ACPI operand cache leak. Signed-off-by: Seunghun Han <kkamagui@gmail.com> Signed-off-by: Erik Schmauss <erik.schmauss@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> |
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| fs | ||
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README
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.