Ubuntu: (Multiple Advisories) (CVE-2025-38344): Linux kernel vulnerabilities

In the Linux kernel, the following vulnerability has been resolved:

ACPICA: fix acpi parse and parseext cache leaks

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/0x3
---truncated---