CVE-2026-89724: media: vicodec: fix out-of-bounds write in FWHT encoder

CVE-2026-89724: media: vicodec: fix out-of-bounds write in FWHT encoder

[Greg Kroah-Hartman]

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

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

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

media: vicodec: fix out-of-bounds write in FWHT encoder

vidioc_s_fmt_vid_out() sizes the encoder CAPTURE buffer from the
compressed descriptor pixfmt_fwht, whose sizeimage_mult is 3:
coded_w * coded_h * 3 + sizeof(struct fwht_cframe_hdr). fwht_encode_frame()
encodes one plane per component, and an incompressible plane takes the
FWHT_FRAME_UNENCODED path in encode_plane(), copying the plane verbatim.

For a 4-component pixel format all four planes are full resolution
(width_div == height_div == 1), so a frame that forces every plane
through the unencoded fallback writes
sizeof(struct fwht_cframe_hdr) + 4 * coded_w * coded_h bytes, overrunning
the plane by coded_w * coded_h, which can result in corruption
of adjacent kernel heap memory.

Bump pixfmt_fwht.sizeimage_mult from 3 to 4, matching the largest
components_num among the supported raw formats, so the capture buffer is
always large enough for the unencoded fallback.

The Linux kernel CVE team has assigned CVE-2026-89724 to this issue.


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

	Issue introduced in 5.0 with commit 16ecf6dff97ce0194a7126e26159492668d47a7e and fixed in 6.12.109 with commit 84cfebf7f4229d748cca8eb9c4e1f1c4099d3ab7
	Issue introduced in 5.0 with commit 16ecf6dff97ce0194a7126e26159492668d47a7e and fixed in 6.18.50 with commit 8c14472431e27f13661d0db9d837156eaced0ecb
	Issue introduced in 5.0 with commit 16ecf6dff97ce0194a7126e26159492668d47a7e and fixed in 7.2.4 with commit b95315ffc66b39856396c1043618bb4e4d5785ba
	Issue introduced in 5.0 with commit 16ecf6dff97ce0194a7126e26159492668d47a7e and fixed in 7.3-rc1 with commit cf4500ebf6fb57bf4ab83c3dd349a40257dbe2a9

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-2026-89724
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/media/test-drivers/vicodec/vicodec-core.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/84cfebf7f4229d748cca8eb9c4e1f1c4099d3ab7
	https://git.kernel.org/stable/c/8c14472431e27f13661d0db9d837156eaced0ecb
	https://git.kernel.org/stable/c/b95315ffc66b39856396c1043618bb4e4d5785ba
	https://git.kernel.org/stable/c/cf4500ebf6fb57bf4ab83c3dd349a40257dbe2a9