francis.wang
4c86c082a2
Combine poky (Yocto scarthgap), meta-openembedded (scarthgap), and meta-openwrt into a single repository. Components: - poky/ Yocto core framework (BitBake + OE-Core) - meta-openembedded/ Community layers (meta-oe, meta-python, meta-networking) - meta-openwrt/ OpenWrt customization layer - setup-env.sh One-click build environment setup - README.md Project documentation
61 lines
2.7 KiB
Diff
61 lines
2.7 KiB
Diff
From 788a624d7387a758ffd5c7ab010f1870dea753a1 Mon Sep 17 00:00:00 2001
|
|
From: Cosmin Truta <ctruta@gmail.com>
|
|
Date: Sat, 29 Nov 2025 00:39:16 +0200
|
|
Subject: [PATCH] Fix an out-of-bounds read in `png_image_read_composite`
|
|
|
|
Add a defensive bounds check before calling PNG_sRGB_FROM_LINEAR to
|
|
prevent reading up to 506 entries (1012 bytes) past `png_sRGB_base[]`.
|
|
|
|
For palette images with gamma, `png_init_read_transformations`
|
|
clears PNG_COMPOSE after compositing on the palette, but it leaves
|
|
PNG_FLAG_OPTIMIZE_ALPHA set. The simplified API then calls
|
|
`png_image_read_composite` with sRGB data (not linear premultiplied),
|
|
causing the index to reach 1017. (The maximum valid index is 511.)
|
|
|
|
NOTE:
|
|
This is a defensive fix that addresses the security issue (out-of-bounds
|
|
read) but *NOT* the correctness issue (wrong output). When the clamp
|
|
triggers, the affected pixels are clamped to white instead of the
|
|
correct composited color. Valid PNG images may render incorrectly with
|
|
the simplified API.
|
|
|
|
TODO:
|
|
We already know the root cause is a flag synchronization error.
|
|
For palette images with gamma, `png_init_read_transformations`
|
|
clears PNG_COMPOSE but leaves PNG_FLAG_OPTIMIZE_ALPHA set, causing
|
|
`png_image_read_composite` to misinterpret sRGB data as linear
|
|
premultiplied. However, we have yet to implement an architectural fix
|
|
that requires coordinating the simplified API with the transformation
|
|
pipeline.
|
|
|
|
Reported-by: flyfish101 <flyfish101@users.noreply.github.com>
|
|
|
|
CVE: CVE-2025-66293
|
|
Upstream-Status: Backport [https://github.com/pnggroup/libpng/commit/788a624d7387a758ffd5c7ab010f1870dea753a1]
|
|
Signed-off-by: Peter Marko <peter.marko@siemens.com>
|
|
---
|
|
pngread.c | 9 +++++++--
|
|
1 file changed, 7 insertions(+), 2 deletions(-)
|
|
|
|
diff --git a/pngread.c b/pngread.c
|
|
index 79917daaa..ab62edd9d 100644
|
|
--- a/pngread.c
|
|
+++ b/pngread.c
|
|
@@ -3406,9 +3406,14 @@ png_image_read_composite(png_voidp argument)
|
|
component += (255-alpha)*png_sRGB_table[outrow[c]];
|
|
|
|
/* So 'component' is scaled by 255*65535 and is
|
|
- * therefore appropriate for the sRGB to linear
|
|
- * conversion table.
|
|
+ * therefore appropriate for the sRGB-to-linear
|
|
+ * conversion table. Clamp to the valid range
|
|
+ * as a defensive measure against an internal
|
|
+ * libpng bug where the data is sRGB rather than
|
|
+ * linear premultiplied.
|
|
*/
|
|
+ if (component > 255*65535)
|
|
+ component = 255*65535;
|
|
component = PNG_sRGB_FROM_LINEAR(component);
|
|
}
|
|
|