ACPI: EC: clean up handlers on probe failure in acpi_ec_setup()

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Summary

CVECVE-2026-31426
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-13 14:16:12 UTC
Updated2026-04-13 15:01:43 UTC
DescriptionIn 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

Risk And Classification

EPSS: 0.000240000 probability, percentile 0.066090000 (date 2026-04-15)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 03e9a0e05739cf872fee494b06c75c0469704a21 022d1727f33ff90b3e1775125264e3023901952e git Not specified
CNA Linux Linux affected 03e9a0e05739cf872fee494b06c75c0469704a21 9c886e63b69658959633937e3acb7ca8addf7499 git Not specified
CNA Linux Linux affected 03e9a0e05739cf872fee494b06c75c0469704a21 808c0f156f48d5b8ca34088cbbfba8444e606cbc git Not specified
CNA Linux Linux affected 03e9a0e05739cf872fee494b06c75c0469704a21 d04c007047c88158141d9bd5eac761cdadd3782c git Not specified
CNA Linux Linux affected 03e9a0e05739cf872fee494b06c75c0469704a21 be1a827e15991e874e0d5222d0ea5fdad01960fe git Not specified
CNA Linux Linux affected 03e9a0e05739cf872fee494b06c75c0469704a21 f6484cadbcaf26b5844b51bd7307a663dda48ef6 git Not specified
CNA Linux Linux affected 5.7 Not specified
CNA Linux Linux unaffected 5.7 semver Not specified
CNA Linux Linux unaffected 6.1.168 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.131 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.80 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.21 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.11 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/808c0f156f48d5b8ca34088cbbfba8444e606cbc 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d04c007047c88158141d9bd5eac761cdadd3782c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/be1a827e15991e874e0d5222d0ea5fdad01960fe 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/022d1727f33ff90b3e1775125264e3023901952e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9c886e63b69658959633937e3acb7ca8addf7499 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f6484cadbcaf26b5844b51bd7307a663dda48ef6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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