| Message ID | 1498191512-125542-1-git-send-email-kkamagui@gmail.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
diff --git a/drivers/acpi/acpica/psobject.c b/drivers/acpi/acpica/psobject.c index 5bcb618..3030c3c 100644 --- a/drivers/acpi/acpica/psobject.c +++ b/drivers/acpi/acpica/psobject.c @@ -680,6 +680,25 @@ acpi_ps_complete_final_op(struct acpi_walk_state *walk_state, (void) acpi_ps_complete_this_op(walk_state, op); + + /* Clean up */ + do { + acpi_ps_pop_scope(& + (walk_state-> + parser_state), + &op, + &walk_state-> + arg_types, + &walk_state-> + arg_count); + + if (op) { + acpi_ps_complete_this_op + (walk_state, op); + } + + } while (op); + return_ACPI_STATUS(status); } }
I'm Seunghun Han, and I work for National Security Research Institute of South Korea. I have been doing a research on ACPI and found an ACPI cache leak in ACPI early abort cases. Boot log of ACPI cache leak is as follows: [ 0.352414] ACPI: Added _OSI(Module Device) [ 0.353182] ACPI: Added _OSI(Processor Device) [ 0.353182] ACPI: Added _OSI(3.0 _SCP Extensions) [ 0.353182] ACPI: Added _OSI(Processor Aggregator Device) [ 0.356028] ACPI: Unable to start the ACPI Interpreter [ 0.356799] ACPI Error: Could not remove SCI handler (20170303/evmisc-281) [ 0.360215] kmem_cache_destroy Acpi-State: Slab cache still has objects [ 0.360648] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 4.12.0-rc4-next-20170608+ #10 [ 0.361273] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 [ 0.361873] Call Trace: [ 0.362243] ? dump_stack+0x5c/0x81 [ 0.362591] ? kmem_cache_destroy+0x1aa/0x1c0 [ 0.362944] ? acpi_sleep_proc_init+0x27/0x27 [ 0.363296] ? acpi_os_delete_cache+0xa/0x10 [ 0.363646] ? acpi_ut_delete_caches+0x6d/0x7b [ 0.364000] ? acpi_terminate+0xa/0x14 [ 0.364000] ? acpi_init+0x2af/0x34f [ 0.364000] ? __class_create+0x4c/0x80 [ 0.364000] ? video_setup+0x7f/0x7f [ 0.364000] ? acpi_sleep_proc_init+0x27/0x27 [ 0.364000] ? do_one_initcall+0x4e/0x1a0 [ 0.364000] ? kernel_init_freeable+0x189/0x20a [ 0.364000] ? rest_init+0xc0/0xc0 [ 0.364000] ? kernel_init+0xa/0x100 [ 0.364000] ? ret_from_fork+0x25/0x30 I analyzed this memory leak in detail. I found that “Acpi-State” cache and “Acpi-Parse” cache were merged because the size of cache objects was same slab cache size. I finally found “Acpi-Parse” cache and “Acpi-ParseExt” cache were leaked using SLAB_NEVER_MERGE flag in kmem_cache_create() function. Real ACPI cache leak point is as follows: [ 0.360101] ACPI: Added _OSI(Module Device) [ 0.360101] ACPI: Added _OSI(Processor Device) [ 0.360101] ACPI: Added _OSI(3.0 _SCP Extensions) [ 0.361043] ACPI: Added _OSI(Processor Aggregator Device) [ 0.364016] ACPI: Unable to start the ACPI Interpreter [ 0.365061] ACPI Error: Could not remove SCI handler (20170303/evmisc-281) [ 0.368174] kmem_cache_destroy Acpi-Parse: Slab cache still has objects [ 0.369332] CPU: 1 PID: 1 Comm: swapper/0 Tainted: G W 4.12.0-rc4-next-20170608+ #8 [ 0.371256] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 [ 0.372000] Call Trace: [ 0.372000] ? dump_stack+0x5c/0x81 [ 0.372000] ? kmem_cache_destroy+0x1aa/0x1c0 [ 0.372000] ? acpi_sleep_proc_init+0x27/0x27 [ 0.372000] ? acpi_os_delete_cache+0xa/0x10 [ 0.372000] ? acpi_ut_delete_caches+0x56/0x7b [ 0.372000] ? acpi_terminate+0xa/0x14 [ 0.372000] ? acpi_init+0x2af/0x34f [ 0.372000] ? __class_create+0x4c/0x80 [ 0.372000] ? video_setup+0x7f/0x7f [ 0.372000] ? acpi_sleep_proc_init+0x27/0x27 [ 0.372000] ? do_one_initcall+0x4e/0x1a0 [ 0.372000] ? kernel_init_freeable+0x189/0x20a [ 0.372000] ? rest_init+0xc0/0xc0 [ 0.372000] ? kernel_init+0xa/0x100 [ 0.372000] ? ret_from_fork+0x25/0x30 [ 0.388039] kmem_cache_destroy Acpi-ParseExt: Slab cache still has objects [ 0.389063] CPU: 1 PID: 1 Comm: swapper/0 Tainted: G W 4.12.0-rc4-next-20170608+ #8 [ 0.390557] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 [ 0.392000] Call Trace: [ 0.392000] ? dump_stack+0x5c/0x81 [ 0.392000] ? kmem_cache_destroy+0x1aa/0x1c0 [ 0.392000] ? acpi_sleep_proc_init+0x27/0x27 [ 0.392000] ? acpi_os_delete_cache+0xa/0x10 [ 0.392000] ? acpi_ut_delete_caches+0x6d/0x7b [ 0.392000] ? acpi_terminate+0xa/0x14 [ 0.392000] ? acpi_init+0x2af/0x34f [ 0.392000] ? __class_create+0x4c/0x80 [ 0.392000] ? video_setup+0x7f/0x7f [ 0.392000] ? acpi_sleep_proc_init+0x27/0x27 [ 0.392000] ? do_one_initcall+0x4e/0x1a0 [ 0.392000] ? kernel_init_freeable+0x189/0x20a [ 0.392000] ? rest_init+0xc0/0xc0 [ 0.392000] ? kernel_init+0xa/0x100 [ 0.392000] ? ret_from_fork+0x25/0x30 When early abort is occurred due to invalid ACPI information, Linux kernel terminates ACPI by calling acpi_terminate() function. The function calls acpi_ut_delete_caches() function to delete local caches (acpi_gbl_namespace_ cache, state_cache, operand_cache, ps_node_cache, ps_node_ext_cache). But the deletion codes in acpi_ut_delete_caches() function only delete slab caches using kmem_cache_destroy() function, therefore the cache objects should be flushed before acpi_ut_delete_caches() function. “Acpi-Parse” cache and “Acpi-ParseExt” cache are used in an AML parse function, acpi_ps_parse_loop(). The function should have flush codes to handle an error state due to invalid AML codes. This cache leak has 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. To fix ACPI cache leak for enhancing security, I made a patch which has flush codes in acpi_ps_parse_loop() function. I hope that this patch improves the security of Linux kernel. Thank you. Signed-off-by: Seunghun Han <kkamagui@gmail.com> --- Changes since v1: move flush code to acpi_ps_complete_final_op() function. drivers/acpi/acpica/psobject.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)