HyeongJun An 86df6499df platform/x86: intel-hid: Protect ACPI notify handler against recursion
commit c085d82613 upstream.

Since commit e2ffcda162 ("ACPI: OSL: Allow Notify () handlers to run on
all CPUs") ACPI notify handlers like the intel-hid notify_handler() may
run on multiple CPU cores racing with themselves.

On convertibles and detachables (matched by DMI chassis-type 31 and 32 in
dmi_auto_add_switch[]) the SW_TABLET_MODE input device is registered
lazily from notify_handler() on the first tablet-mode event, via
intel_hid_switches_setup(). When two such events race on different CPUs
both can pass the !priv->switches check and register the priv->switches
input device twice, resulting in a duplicate sysfs entry and a subsequent
NULL pointer dereference.

This is the same class of bug fixed by commit e075c3b13a ("platform/x86:
intel-vbtn: Protect ACPI notify handler against recursion") for the
sibling intel-vbtn driver.

Protect intel-hid notify_handler() from racing with itself with a mutex
to fix this.

Fixes: e2ffcda162 ("ACPI: OSL: Allow Notify () handlers to run on all CPUs")
Cc: stable@vger.kernel.org
Signed-off-by: HyeongJun An <sammiee5311@gmail.com>
Link: https://patch.msgid.link/20260605174905.131095-1-sammiee5311@gmail.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-07-18 16:53:06 +02:00
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2026-07-04 13:44:22 +02:00
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Linux kernel
============

There are several guides for kernel developers and users. These guides can
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In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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