Commit 1e0e629e authored Mar 26, 2025 by Seunghun Han Committed by Greg Kroah-Hartman Jun 27, 2025

ACPICA: fix acpi parse and parseext cache leaks

[ Upstream commit bed18f0bdcd6737a938264a59d67923688696fc4 ]

ACPICA commit 8829e70e1360c81e7a5a901b5d4f48330e021ea5

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 gmb_h virtual_box/virtual_box, BIOS
virtual_box 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-parse_ext” 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 gmb_h virtual_box/virtual_box, BIOS
virtual_box 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-parse_ext: 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 gmb_h virtual_box/virtual_box, BIOS
virtual_box 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 complete all ops
using acpi_ps_complete_final_op() when an error occurs due to invalid
AML codes.
However, the current implementation of acpi_ps_complete_final_op() does not
complete all ops when it meets some errors and this cause cache leak.

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 to complete all
ops unconditionally for acpi_ps_complete_final_op() function.

I hope that this patch improves the security of Linux kernel.

Thank you.

Link: https://github.com/acpica/acpica/commit/8829e70e


Signed-off-by: Seunghun Han <kkamagui@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://patch.msgid.link/2363774.ElGaqSPkdT@rjwysocki.net


Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 2ca55d22

drivers/acpi/acpica/psobject.c

+15 −37

Original line number	Original line	Diff line number	Diff line
	@@ -639,7 +639,8 @@ acpi_status
	acpi_ps_complete_final_op(struct acpi_walk_state *walk_state,		acpi_ps_complete_final_op(struct acpi_walk_state *walk_state,
	union acpi_parse_object *op, acpi_status status)		union acpi_parse_object *op, acpi_status status)
	{		{
	acpi_status status2;		acpi_status return_status = status;
			u8 ascending = TRUE;

	ACPI_FUNCTION_TRACE_PTR(ps_complete_final_op, walk_state);		ACPI_FUNCTION_TRACE_PTR(ps_complete_final_op, walk_state);

	@@ -653,7 +654,7 @@ acpi_ps_complete_final_op(struct acpi_walk_state *walk_state,
	op));		op));
	do {		do {
	if (op) {		if (op) {
	if (walk_state->ascending_callback != NULL) {		if (ascending && walk_state->ascending_callback != NULL) {
	walk_state->op = op;		walk_state->op = op;
	walk_state->op_info =		walk_state->op_info =
	acpi_ps_get_opcode_info(op->common.		acpi_ps_get_opcode_info(op->common.
	@@ -675,49 +676,26 @@ acpi_ps_complete_final_op(struct acpi_walk_state *walk_state,
	}		}

	if (status == AE_CTRL_TERMINATE) {		if (status == AE_CTRL_TERMINATE) {
	status = AE_OK;		ascending = FALSE;
			return_status = AE_CTRL_TERMINATE;
	/* Clean up */
	do {
	if (op) {
	status2 =
	acpi_ps_complete_this_op
	(walk_state, op);
	if (ACPI_FAILURE
	(status2)) {
	return_ACPI_STATUS
	(status2);
	}
	}

	acpi_ps_pop_scope(&
	(walk_state->
	parser_state),
	&op,
	&walk_state->
	arg_types,
	&walk_state->
	arg_count);

	} while (op);

	return_ACPI_STATUS(status);
	}		}

	else if (ACPI_FAILURE(status)) {		else if (ACPI_FAILURE(status)) {

	/* First error is most important */		/* First error is most important */

	(void)		ascending = FALSE;
	acpi_ps_complete_this_op(walk_state,		return_status = status;
	op);
	return_ACPI_STATUS(status);
	}		}
	}		}

	status2 = acpi_ps_complete_this_op(walk_state, op);		status = acpi_ps_complete_this_op(walk_state, op);
	if (ACPI_FAILURE(status2)) {		if (ACPI_FAILURE(status)) {
	return_ACPI_STATUS(status2);		ascending = FALSE;
			if (ACPI_SUCCESS(return_status) \|\|
			return_status == AE_CTRL_TERMINATE) {
			return_status = status;
			}
	}		}
	}		}

	@@ -727,5 +705,5 @@ acpi_ps_complete_final_op(struct acpi_walk_state *walk_state,

	} while (op);		} while (op);

	return_ACPI_STATUS(status);		return_ACPI_STATUS(return_status);
	}		}