CVE-2026-80575: Input: cs40l50-vibra - validate custom data from user space

CVE-2026-80575: Input: cs40l50-vibra - validate custom data from user space

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

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

Input: cs40l50-vibra - validate custom data from user space

cs40l50_add() copies the custom data of an FF_PERIODIC/FF_CUSTOM effect
straight from the ff_effect the user passed to EVIOCSFF, without
requiring it to hold anything:

    work_data.custom_data = memdup_array_user(periodic->custom_data,
                                              periodic->custom_len,
                                              sizeof(s16));
    work_data.custom_len = periodic->custom_len;

The driver then reads two words out of that buffer: custom_data[0] as the
waveform bank in cs40l50_effect_bank_set(), and custom_data[1] as the
index within the bank in cs40l50_effect_index_set().  Neither read is
covered by a length check, and custom_len is fully user controlled:

  - custom_len == 0 makes memdup_array_user() call memdup_user() with a
    length of zero, which returns ZERO_SIZE_PTR rather than an error, so
    custom_data[0] dereferences it.

  - custom_len == 1 allocates two bytes.  A bank of ROM or RAM keeps
    effect->type out of the OWT case, and custom_data[1] is then read one
    word past the allocation.

The bank value itself is also mishandled.  It is masked with
CS40L50_CUSTOM_DATA_MASK (0xffff) but stored in an s16, so a
custom_data[0] of 0x8000 or above wraps to a negative value that passes
the "bank_type >= CS40L50_WVFRM_BANK_NUM" test.
cs40l50_effect_index_set() indexes vib->dsp.banks[] with it before the
switch statement's default case gets a chance to reject it:

    base_index = vib->dsp.banks[effect->type].base_index;
    max_index = vib->dsp.banks[effect->type].max_index;

Require the two words the driver reads to be present, and hold the masked
bank in a u32 so the existing upper-bound test covers the whole range.
The da7280 haptic driver already range checks custom_len this way.

The Linux kernel CVE team has assigned CVE-2026-80575 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.11 with commit c38fe1bb5d21c2ce0857965ee06174ee587d6b42 and fixed in 6.12.105 with commit 3855b6a11f8a7aceb8181cc08c99afef58517006
	Issue introduced in 6.11 with commit c38fe1bb5d21c2ce0857965ee06174ee587d6b42 and fixed in 6.18.46 with commit 52a818c586ae2c36b7324bfaefb547f5e866a8ae
	Issue introduced in 6.11 with commit c38fe1bb5d21c2ce0857965ee06174ee587d6b42 and fixed in 7.1.10 with commit d38554602a0b04e85fad28ce72c7500cf50d419b
	Issue introduced in 6.11 with commit c38fe1bb5d21c2ce0857965ee06174ee587d6b42 and fixed in 7.2 with commit 7d5c576cb1c86047b1fcb1aa9532e17fc5e46c1d

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-80575
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/input/misc/cs40l50-vibra.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/3855b6a11f8a7aceb8181cc08c99afef58517006
	https://git.kernel.org/stable/c/52a818c586ae2c36b7324bfaefb547f5e866a8ae
	https://git.kernel.org/stable/c/d38554602a0b04e85fad28ce72c7500cf50d419b
	https://git.kernel.org/stable/c/7d5c576cb1c86047b1fcb1aa9532e17fc5e46c1d