CVE-2026-64565: Input: ims-pcu - fix heap-buffer-overflow in ims_pcu_process_data()

From: Greg Kroah-Hartman <[email protected]>

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

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

Input: ims-pcu - fix heap-buffer-overflow in ims_pcu_process_data()

The `ims_pcu_process_data()` processes incoming URB data byte by byte.
However, it fails to check if the `read_pos` index exceeds
IMS_PCU_BUF_SIZE.

If a malicious USB device sends a packet larger than IMS_PCU_BUF_SIZE,
`read_pos` will increment indefinitely. Moreover, since `read_pos` is
located immediately after `read_buf`, the attacker can overwrite
`read_pos` itself to arbitrarily control the index.

This manipulated `read_pos` is subsequently used in
`ims_pcu_handle_response()` to copy data into `cmd_buf`, leading to a
heap buffer overflow.

Specifically, an attacker can overwrite the `cmd_done.wait.head` located
at offset 136 relative to `cmd_buf` in the `ims_pcu_handle_response()`.
Consequently, when the driver calls `complete(&pcu->cmd_done)`, it
triggers a control flow hijack by using the manipulated pointer.

Fix this by adding a bounds check for `read_pos` before writing to
`read_buf`. If the packet is too long, discard it, log a warning,
and reset the parser state.

[dtor: factor out resetting packet state, reset checksum as well]

The Linux kernel CVE team has assigned CVE-2026-64565 to this issue.


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

	Issue introduced in 3.10 with commit 628329d52474323938a03826941e166bc7c8eff4 and fixed in 6.6.148 with commit 40bbbf2e91fd60715525bf0405c67876af817edf
	Issue introduced in 3.10 with commit 628329d52474323938a03826941e166bc7c8eff4 and fixed in 6.12.101 with commit ca9f8c09845fb8c51b6d447f6428eecd1b8b0a49
	Issue introduced in 3.10 with commit 628329d52474323938a03826941e166bc7c8eff4 and fixed in 6.18.42 with commit d03a740e087de7dcb2a26dc1123377bd3d1d84ca
	Issue introduced in 3.10 with commit 628329d52474323938a03826941e166bc7c8eff4 and fixed in 7.1 with commit 875115b82c295277b81b6dfee7debc725f44e854

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-2026-64565
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/ims-pcu.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/40bbbf2e91fd60715525bf0405c67876af817edf
	https://git.kernel.org/stable/c/ca9f8c09845fb8c51b6d447f6428eecd1b8b0a49
	https://git.kernel.org/stable/c/d03a740e087de7dcb2a26dc1123377bd3d1d84ca
	https://git.kernel.org/stable/c/875115b82c295277b81b6dfee7debc725f44e854