CVE-2026-68365: USB: serial: io_edgeport: cap received transmit credits

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

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

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

USB: serial: io_edgeport: cap received transmit credits

The interrupt-status packet reports transmit credits returned by the
device. edge_interrupt_callback() adds the 16-bit value to txCredits
without checking maxTxCredits.

edge_write() uses txCredits minus the software FIFO count as the amount
of data that fits. Since the FIFO is allocated with maxTxCredits bytes,
txCredits exceeding maxTxCredits can cause OOB write in ring buffer.

Cap accumulated credits at maxTxCredits. Conforming devices should never
hit the cap.

The Linux kernel CVE team has assigned CVE-2026-68365 to this issue.


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

	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.6.148 with commit ee57992c053a6d395e98ced2d4c9cc3b42d8c27a
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.12.101 with commit 64b687f9694777754285d489abbefa3784bc78da
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.18.42 with commit cbe00048b69d67c8a78293cb7681b4c9963b26c7
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 7.1.6 with commit 1e47d8228b8767c8ac722aedb388f70adeeda43d
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 7.2-rc5 with commit faaddd811c5099f11a5f52e68a6b31a5898cda4f

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-2026-68365
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/usb/serial/io_edgeport.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/ee57992c053a6d395e98ced2d4c9cc3b42d8c27a
	https://git.kernel.org/stable/c/64b687f9694777754285d489abbefa3784bc78da
	https://git.kernel.org/stable/c/cbe00048b69d67c8a78293cb7681b4c9963b26c7
	https://git.kernel.org/stable/c/1e47d8228b8767c8ac722aedb388f70adeeda43d
	https://git.kernel.org/stable/c/faaddd811c5099f11a5f52e68a6b31a5898cda4f