CVE-2026-89730: fpga: altera-cvp: Avoid out-of-bounds read in trailing byte write

CVE-2026-89730: fpga: altera-cvp: Avoid out-of-bounds read in trailing byte write

[Greg Kroah-Hartman]

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

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

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

fpga: altera-cvp: Avoid out-of-bounds read in trailing byte write

The trailing byte path in altera_cvp_send_block() dereferences a u32
pointer even when only 1-3 bytes remain in the input buffer. If the buffer
ends at a page or scatterlist boundary, this can read past the valid image
data and fault.

Copy the remaining bytes into a zero-initialized u32 before writing the
final word so only valid bytes are read from the input buffer.

The Linux kernel CVE team has assigned CVE-2026-89730 to this issue.


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

	Issue introduced in 4.14 with commit 34d1dc17ce978ae76e676d401b48fe9d004aa948 and fixed in 6.12.109 with commit b138bc665e21d4422382ab43aebdf0a2b7bb9cb3
	Issue introduced in 4.14 with commit 34d1dc17ce978ae76e676d401b48fe9d004aa948 and fixed in 6.18.50 with commit 827ec385458adeeda651de2b6f3537e386b1a8d9
	Issue introduced in 4.14 with commit 34d1dc17ce978ae76e676d401b48fe9d004aa948 and fixed in 7.2.4 with commit 4dc1051939e499c838229af035464a5fc7671198
	Issue introduced in 4.14 with commit 34d1dc17ce978ae76e676d401b48fe9d004aa948 and fixed in 7.3-rc1 with commit 9da70a43b5fea60d758137f7f0ccfe19356cb5bb

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-2026-89730
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/fpga/altera-cvp.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/b138bc665e21d4422382ab43aebdf0a2b7bb9cb3
	https://git.kernel.org/stable/c/827ec385458adeeda651de2b6f3537e386b1a8d9
	https://git.kernel.org/stable/c/4dc1051939e499c838229af035464a5fc7671198
	https://git.kernel.org/stable/c/9da70a43b5fea60d758137f7f0ccfe19356cb5bb