[PATCH] Add clamping to QColorTransferGenericFunction

This ensures that the inputs are within range for the use of these
function.

Depending on the values passed, they can trigger FE_INVALID errors
and thus NaN as return values.

This can happen for example when feeding an invalid ICC profile to
QColorSpace::fromIccProfile.

Credit to OSS-Fuzz

Fixes: QTBUG-137159
Origin: upstream, https://download.qt.io/official_releases/qt/6.8/CVE-2025-5992-qtbase-6.8.patch

Gbp-Pq: Name upstream_cve-2025-5992_input_range_qcolortransformation.diff

[PATCH] QColorTransferGeneric: fix the BT.2100 PQ EOTF

The PQ EOTF formula for BT.2100 [1][2] was incorrect. Fix it; while at
it, rename the variables to match the symbols used in the original
formula.

The inverse EOTF was correct, but also rename the variables there (for
the same reason).

[1] https://www.itu.int/rec/R-REC-BT.2100-2-201807-I/en
[2] https://en.wikipedia.org/wiki/Perceptual_quantizer#Technical_details

Change-Id: I6ce3a609824bee82053a16b3ff3cfc7cb396ce8f
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
(cherry picked from commit a7ff4679facb9a44dff8b63a7e461ababa6aedfb)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit 35c18eba64b6220e36ea14d32b911342e9d0921c)
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Gbp-Pq: Name upstream_QColorTransferGeneric_fix_BT2100PQEOTF.patch

qt6-base (6.8.2+dfsg-9) unstable; urgency=medium

  [ Patrick Franz ]
  * Backport patch to fix the PQ EOTF formula for BT.2100. This patch is
    needed to make the patch for CVE-2025-5992 applicable.
  * Backport patch to fix CVE-2025-5992 (Closes: #1109299).

[dgit import unpatched qt6-base 6.8.2+dfsg-9]

Import qt6-base_6.8.2+dfsg-9.debian.tar.xz

[dgit import tarball qt6-base 6.8.2+dfsg-9 qt6-base_6.8.2+dfsg-9.debian.tar.xz]

Import qt6-base_6.8.2+dfsg.orig.tar.xz

[dgit import orig qt6-base_6.8.2+dfsg.orig.tar.xz]