libpng: patch CVE-2026-22801

Pick comit per [1].

[1] https://github.com/pnggroup/libpng/security/advisories/GHSA-vgjq-8cw5-ggw8

(From OE-Core rev: fc0f0ecb694ae3042cff4472c62c78a7389662c6)

Signed-off-by: Peter Marko <peter.marko@siemens.com>
Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
Signed-off-by: Paul Barker <paul@pbarker.dev>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 174 insertions, 0 deletions

diff --git a/meta/recipes-multimedia/libpng/files/CVE-2026-22801.patch b/meta/recipes-multimedia/libpng/files/CVE-2026-22801.patch
new file mode 100644
index 0000000000..8a611ac749
--- /dev/null
+++ b/meta/recipes-multimedia/libpng/files/CVE-2026-22801.patch
@@ -0,0 +1,173 @@
+From cf155de014fc6c5cb199dd681dd5c8fb70429072 Mon Sep 17 00:00:00 2001
+From: Cosmin Truta <ctruta@gmail.com>
+Date: Sat, 10 Jan 2026 15:20:18 +0200
+Subject: [PATCH] fix: Remove incorrect truncation casts from
+ `png_write_image_*`
+
+The type of the row stride (`display->row_bytes`) is ptrdiff_t. Casting
+to png_uint_16 before division will truncate large strides, causing
+incorrect pointer arithmetic for images exceeding 65535 bytes per row.
+For bottom-up images (negative stride), the truncation also corrupts
+the sign, advancing the row pointer forward instead of backward.
+
+Remove the erroneous casts and let the compiler handle the pointer
+arithmetic correctly. Also replace `sizeof (png_uint_16)` with 2.
+
+Add regression test via `pngstest --stride-extra N` where N > 32767
+triggers the affected code paths.
+
+A NOTE ABOUT HISTORY:
+The original code in libpng 1.5.6 (2011) had no such casts. They were
+introduced in libpng 1.6.26 (2016), likely to silence compiler warnings
+on 16-bit systems where the cast would be a no-op. On 32/64-bit systems
+the cast truncates the strides above 65535 and corrupts the negative
+strides.
+
+CVE: CVE-2026-22801
+Upstream-Status: Backport [https://github.com/pnggroup/libpng/commit/cf155de014fc6c5cb199dd681dd5c8fb70429072]
+Signed-off-by: Peter Marko <peter.marko@siemens.com>
+---
+ CMakeLists.txt              |  9 ++++++++-
+ contrib/libtests/pngstest.c | 29 ++++++++++++++++++++++++++++-
+ pngwrite.c                  | 10 +++++-----
+ tests/pngstest-large-stride |  8 ++++++++
+ 4 files changed, 49 insertions(+), 7 deletions(-)
+ create mode 100755 tests/pngstest-large-stride
+
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index a8cd82402..a595ed91d 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -1,7 +1,7 @@
+ 
+ # CMakeLists.txt - CMake lists for libpng
+ #
+-# Copyright (c) 2018-2024 Cosmin Truta.
++# Copyright (c) 2018-2026 Cosmin Truta
+ # Copyright (c) 2007-2018 Glenn Randers-Pehrson.
+ # Originally written by Christian Ehrlicher, 2007.
+ #
+@@ -859,6 +859,13 @@ if(PNG_TESTS AND PNG_SHARED)
+     endforeach()
+   endforeach()
+ 
++  # Regression test:
++  # Use stride_extra > 32767 to trigger row_bytes > 65535 for linear images.
++  png_add_test(NAME pngstest-large-stride
++               COMMAND pngstest
++               OPTIONS --stride-extra 33000 --tmpfile "large-stride-" --log
++               FILES "${CMAKE_CURRENT_SOURCE_DIR}/contrib/testpngs/rgb-alpha-16-linear.png")
++
+   add_executable(pngunknown ${pngunknown_sources})
+   target_link_libraries(pngunknown PRIVATE png_shared)
+ 
+diff --git a/contrib/libtests/pngstest.c b/contrib/libtests/pngstest.c
+index ff4c2b24a..2f29afee2 100644
+--- a/contrib/libtests/pngstest.c
++++ b/contrib/libtests/pngstest.c
+@@ -1,7 +1,7 @@
+ 
+ /* pngstest.c
+  *
+- * Copyright (c) 2021 Cosmin Truta
++ * Copyright (c) 2021-2026 Cosmin Truta
+  * Copyright (c) 2013-2017 John Cunningham Bowler
+  *
+  * This code is released under the libpng license.
+@@ -3571,6 +3571,33 @@ main(int argc, char **argv)
+          opts |= NO_RESEED;
+       else if (strcmp(arg, "--fault-gbg-warning") == 0)
+          opts |= GBG_ERROR;
++      else if (strcmp(arg, "--stride-extra") == 0)
++      {
++         if (c+1 < argc)
++         {
++            char *ep;
++            unsigned long val = strtoul(argv[++c], &ep, 0);
++
++            if (ep > argv[c] && *ep == 0 && val <= 65535)
++               stride_extra = (int)val;
++
++            else
++            {
++               fflush(stdout);
++               fprintf(stderr, "%s: bad argument for --stride-extra: %s\n",
++                  argv[0], argv[c]);
++               exit(99);
++            }
++         }
++
++         else
++         {
++            fflush(stdout);
++            fprintf(stderr, "%s: missing argument for --stride-extra\n",
++               argv[0]);
++            exit(99);
++         }
++      }
+       else if (strcmp(arg, "--tmpfile") == 0)
+       {
+          if (c+1 < argc)
+diff --git a/pngwrite.c b/pngwrite.c
+index 08066bcc4..a95b846c8 100644
+--- a/pngwrite.c
++++ b/pngwrite.c
+@@ -1,7 +1,7 @@
+ 
+ /* pngwrite.c - general routines to write a PNG file
+  *
+- * Copyright (c) 2018-2024 Cosmin Truta
++ * Copyright (c) 2018-2026 Cosmin Truta
+  * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
+  * Copyright (c) 1996-1997 Andreas Dilger
+  * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
+@@ -1645,7 +1645,7 @@ png_write_image_16bit(png_voidp argument)
+       }
+ 
+       png_write_row(png_ptr, png_voidcast(png_const_bytep, display->local_row));
+-      input_row += (png_uint_16)display->row_bytes/(sizeof (png_uint_16));
++      input_row += display->row_bytes / 2;
+    }
+ 
+    return 1;
+@@ -1771,7 +1771,7 @@ png_write_image_8bit(png_voidp argument)
+ 
+          png_write_row(png_ptr, png_voidcast(png_const_bytep,
+              display->local_row));
+-         input_row += (png_uint_16)display->row_bytes/(sizeof (png_uint_16));
++         input_row += display->row_bytes / 2;
+       } /* while y */
+    }
+ 
+@@ -1796,7 +1796,7 @@ png_write_image_8bit(png_voidp argument)
+          }
+ 
+          png_write_row(png_ptr, output_row);
+-         input_row += (png_uint_16)display->row_bytes/(sizeof (png_uint_16));
++         input_row += display->row_bytes / 2;
+       }
+    }
+ 
+@@ -2115,7 +2115,7 @@ png_image_write_main(png_voidp argument)
+       ptrdiff_t row_bytes = display->row_stride;
+ 
+       if (linear != 0)
+-         row_bytes *= (sizeof (png_uint_16));
++         row_bytes *= 2;
+ 
+       if (row_bytes < 0)
+          row += (image->height-1) * (-row_bytes);
+diff --git a/tests/pngstest-large-stride b/tests/pngstest-large-stride
+new file mode 100755
+index 000000000..7958c5b42
+--- /dev/null
++++ b/tests/pngstest-large-stride
+@@ -0,0 +1,8 @@
++#!/bin/sh
++
++# Regression test:
++# Use stride_extra > 32767 to trigger row_bytes > 65535 for linear images.
++exec ./pngstest \
++     --stride-extra 33000 \
++     --tmpfile "large-stride-" \
++     --log "${srcdir}/contrib/testpngs/rgb-alpha-16-linear.png"
diff --git a/meta/recipes-multimedia/libpng/libpng_1.6.42.bb b/meta/recipes-multimedia/libpng/libpng_1.6.42.bb
index fe99e5df09..0e375a0ce8 100644
--- a/meta/recipes-multimedia/libpng/libpng_1.6.42.bb
+++ b/meta/recipes-multimedia/libpng/libpng_1.6.42.bb
@@ -22,6 +22,7 @@ SRC_URI = "${SOURCEFORGE_MIRROR}/project/${BPN}/${BPN}${LIBV}/${PV}/${BP}.tar.xz
            file://CVE-2025-66293-01.patch \
            file://CVE-2025-66293-02.patch \
            file://CVE-2026-22695.patch \
+           file://CVE-2026-22801.patch \
 "
 
 SRC_URI[sha256sum] = "c919dbc11f4c03b05aba3f8884d8eb7adfe3572ad228af972bb60057bdb48450"