CVE-2026-31426
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: ACPI: EC: clean up handlers on probe failure in acpi_ec_setup() When ec_install_handlers() returns -EPROBE_DEFER on reduced-hardware platforms, it has already started the EC and installed the address space handler with the struct acpi_ec pointer as handler context. However, acpi_ec_setup() propagates the error without any cleanup. The caller acpi_ec_add() then frees the struct acpi_ec for non-boot instances, leaving a dangling handler context in ACPICA. Any subsequent AML evaluation that accesses an EC OpRegion field dispatches into acpi_ec_space_handler() with the freed pointer, causing a use-after-free: BUG: KASAN: slab-use-after-free in mutex_lock (kernel/locking/mutex.c:289) Write of size 8 at addr ffff88800721de38 by task init/1 Call Trace: <TASK> mutex_lock (kernel/locking/mutex.c:289) acpi_ec_space_handler (drivers/acpi/ec.c:1362) acpi_ev_address_space_dispatch (drivers/acpi/acpica/evregion.c:293) acpi_ex_access_region (drivers/acpi/acpica/exfldio.c:246) acpi_ex_field_datum_io (drivers/acpi/acpica/exfldio.c:509) acpi_ex_extract_from_field (drivers/acpi/acpica/exfldio.c:700) acpi_ex_read_data_from_field (drivers/acpi/acpica/exfield.c:327) acpi_ex_resolve_node_to_value (drivers/acpi/acpica/exresolv.c:392) </TASK> Allocated by task 1: acpi_ec_alloc (drivers/acpi/ec.c:1424) acpi_ec_add (drivers/acpi/ec.c:1692) Freed by task 1: kfree (mm/slub.c:6876) acpi_ec_add (drivers/acpi/ec.c:1751) The bug triggers on reduced-hardware EC platforms (ec->gpe < 0) when the GPIO IRQ provider defers probing. Once the stale handler exists, any unprivileged sysfs read that causes AML to touch an EC OpRegion (battery, thermal, backlight) exercises the dangling pointer. Fix this by calling ec_remove_handlers() in the error path of acpi_ec_setup() before clearing first_ec. ec_remove_handlers() checks each EC_FLAGS_* bit before acting, so it is safe to call regardless of how far ec_install_handlers() progressed: -ENODEV (handler not installed): only calls acpi_ec_stop() -EPROBE_DEFER (handler installed): removes handler, stops EC
Severity
HIGH
CVSS score
7.0
(v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-04-13 14:16:12.600000
Last modified
2026-10-19 19:17:53.040000
View original CVE JSON
{
"id": "CVE-2026-31426",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-04-13T14:16:12.600",
"lastModified": "2026-10-19T19:17:53.040",
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{
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nACPI: EC: clean up handlers on probe failure in acpi_ec_setup()\n\nWhen ec_install_handlers() returns -EPROBE_DEFER on reduced-hardware\nplatforms, it has already started the EC and installed the address\nspace handler with the struct acpi_ec pointer as handler context.\nHowever, acpi_ec_setup() propagates the error without any cleanup.\n\nThe caller acpi_ec_add() then frees the struct acpi_ec for non-boot\ninstances, leaving a dangling handler context in ACPICA.\n\nAny subsequent AML evaluation that accesses an EC OpRegion field\ndispatches into acpi_ec_space_handler() with the freed pointer,\ncausing a use-after-free:\n\n BUG: KASAN: slab-use-after-free in mutex_lock (kernel/locking/mutex.c:289)\n Write of size 8 at addr ffff88800721de38 by task init/1\n Call Trace:\n <TASK>\n mutex_lock (kernel/locking/mutex.c:289)\n acpi_ec_space_handler (drivers/acpi/ec.c:1362)\n acpi_ev_address_space_dispatch (drivers/acpi/acpica/evregion.c:293)\n acpi_ex_access_region (drivers/acpi/acpica/exfldio.c:246)\n acpi_ex_field_datum_io (drivers/acpi/acpica/exfldio.c:509)\n acpi_ex_extract_from_field (drivers/acpi/acpica/exfldio.c:700)\n acpi_ex_read_data_from_field (drivers/acpi/acpica/exfield.c:327)\n acpi_ex_resolve_node_to_value (drivers/acpi/acpica/exresolv.c:392)\n </TASK>\n\n Allocated by task 1:\n acpi_ec_alloc (drivers/acpi/ec.c:1424)\n acpi_ec_add (drivers/acpi/ec.c:1692)\n\n Freed by task 1:\n kfree (mm/slub.c:6876)\n acpi_ec_add (drivers/acpi/ec.c:1751)\n\nThe bug triggers on reduced-hardware EC platforms (ec->gpe < 0)\nwhen the GPIO IRQ provider defers probing. Once the stale handler\nexists, any unprivileged sysfs read that causes AML to touch an\nEC OpRegion (battery, thermal, backlight) exercises the dangling\npointer.\n\nFix this by calling ec_remove_handlers() in the error path of\nacpi_ec_setup() before clearing first_ec. ec_remove_handlers()\nchecks each EC_FLAGS_* bit before acting, so it is safe to call\nregardless of how far ec_install_handlers() progressed:\n\n -ENODEV (handler not installed): only calls acpi_ec_stop()\n -EPROBE_DEFER (handler installed): removes handler, stops EC"
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