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ACPICA: fix acpi parse and parseext cache leaks
authorSeunghun Han <kkamagui@gmail.com>
Wed, 26 Mar 2025 20:06:21 +0000 (21:06 +0100)
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>
Thu, 27 Mar 2025 12:17:17 +0000 (13:17 +0100)
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
drivers/acpi/acpica/psobject.c patch | blob | blame | history

diff --git a/drivers/acpi/acpica/psobject.c b/drivers/acpi/acpica/psobject.c
index 54471083ba545ead0b265e1bddb8e56fadc1e6f6..0bce1baaa62b3293ee72b0b334b6c49a537ea3a7 100644 (file)
--- a/drivers/acpi/acpica/psobject.c
+++ b/drivers/acpi/acpica/psobject.c
@@ -636,7 +636,8 @@ acpi_status
 acpi_ps_complete_final_op(struct acpi_walk_state *walk_state,
                          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);
 
@@ -650,7 +651,7 @@ acpi_ps_complete_final_op(struct acpi_walk_state *walk_state,
                          op));
        do {
                if (op) {
-                       if (walk_state->ascending_callback != NULL) {
+                       if (ascending && walk_state->ascending_callback != NULL) {
                                walk_state->op = op;
                                walk_state->op_info =
                                    acpi_ps_get_opcode_info(op->common.
@@ -672,49 +673,26 @@ acpi_ps_complete_final_op(struct acpi_walk_state *walk_state,
                                }
 
                                if (status == AE_CTRL_TERMINATE) {
-                                       status = AE_OK;
-
-                                       /* 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);
+                                       ascending = FALSE;
+                                       return_status = AE_CTRL_TERMINATE;
                                }
 
                                else if (ACPI_FAILURE(status)) {
 
                                        /* First error is most important */
 
-                                       (void)
-                                           acpi_ps_complete_this_op(walk_state,
-                                                                    op);
-                                       return_ACPI_STATUS(status);
+                                       ascending = FALSE;
+                                       return_status = status;
                                }
                        }
 
-                       status2 = acpi_ps_complete_this_op(walk_state, op);
-                       if (ACPI_FAILURE(status2)) {
-                               return_ACPI_STATUS(status2);
+                       status = acpi_ps_complete_this_op(walk_state, op);
+                       if (ACPI_FAILURE(status)) {
+                               ascending = FALSE;
+                               if (ACPI_SUCCESS(return_status) ||
+                                   return_status == AE_CTRL_TERMINATE) {
+                                       return_status = status;
+                               }
                        }
                }
 
@@ -724,5 +702,5 @@ acpi_ps_complete_final_op(struct acpi_walk_state *walk_state,
 
        } while (op);
 
-       return_ACPI_STATUS(status);
+       return_ACPI_STATUS(return_status);
 }
Linux 6.x block layer and io_uring tree(s)