Pick patch according to [2] [1] https://nvd.nist.gov/vuln/detail/CVE-2026-56002 [2] https://security-tracker.debian.org/tracker/CVE-2026-56002
Signed-off-by: Vijay Anusuri <[email protected]> --- .../xorg-lib/libxfont2/CVE-2026-56002.patch | 138 ++++++++++++++++++ .../xorg-lib/libxfont2_2.0.6.bb | 1 + 2 files changed, 139 insertions(+) create mode 100644 meta/recipes-graphics/xorg-lib/libxfont2/CVE-2026-56002.patch diff --git a/meta/recipes-graphics/xorg-lib/libxfont2/CVE-2026-56002.patch b/meta/recipes-graphics/xorg-lib/libxfont2/CVE-2026-56002.patch new file mode 100644 index 0000000000..c0fbb00862 --- /dev/null +++ b/meta/recipes-graphics/xorg-lib/libxfont2/CVE-2026-56002.patch @@ -0,0 +1,138 @@ +From b4389e0b1d84a690b819bb27b1439968811a3674f Mon Sep 17 00:00:00 2001 +From: Peter Hutterer <[email protected]> +Date: Mon, 1 Jun 2026 16:48:40 +1000 +Subject: [PATCH] pcfread: validate bitmap sizes and offsets against per-glyph + metrics + +pcfReadFont() uses bitmapSizes[] read directly from the PCF file to +allocate the repadded bitmap buffer. However, per-glyph metrics (also +from the file) control how much data RepadBitmap() writes. A malicious +PCF font can declare a small bitmapSizes[] value while having per-glyph +metrics that require more space, causing a heap buffer overflow. + +A similar issue happens with the encoding offsets: pcfReadFont reads +encoding offsets from the PCF file and uses them to index into the +metrics array without bounds checking. A crafted font can set an +encoding offset larger than nmetrics, causing an out-of-bounds pointer +that is later dereferenced when glyphs are accessed through the encoding +table. + +And the no-repad bitmap path (when PCF_GLYPH_PAD matches the requested +glyph pad) only validated that each glyph's offset was within the bitmap +buffer, but did not check that the full glyph extent (offset + +BYTES_PER_ROW * height) fits within the buffer. A crafted font with a +glyph offset near the end of a small bitmap buffer but large glyph +metrics causes a heap buffer over-read when the glyph is later rendered. + +This vulnerability was discovered by: + Anonymous working with TrendAI Zero Day Initiative + +CVE-2026-56002/ZDI-CAN-30559 + +Assisted-by: Claude:claude-opus-4-6 +Signed-off-by: Peter Hutterer <[email protected]> +Part-of: <https://gitlab.freedesktop.org/xorg/lib/libxfont/-/merge_requests/34> + +Upstream-Status: Backport [https://gitlab.freedesktop.org/xorg/lib/libxfont/-/commit/b4389e0b1d84a690b819bb27b1439968811a3674] +CVE: CVE-2026-56002 +Signed-off-by: Vijay Anusuri <[email protected]> +--- + src/bitmap/pcfread.c | 59 +++++++++++++++++++++++++++++++++++++++++--- + 1 file changed, 56 insertions(+), 3 deletions(-) + +diff --git a/src/bitmap/pcfread.c b/src/bitmap/pcfread.c +index 882318b..bcb82b8 100644 +--- a/src/bitmap/pcfread.c ++++ b/src/bitmap/pcfread.c +@@ -531,25 +531,74 @@ pcfReadFont(FontPtr pFont, FontFilePtr file, + int old, + new; + xCharInfo *metric; ++ int srcPad = PCF_GLYPH_PAD(format); + +- sizepadbitmaps = bitmapSizes[PCF_SIZE_TO_INDEX(glyph)]; +- padbitmaps = malloc(sizepadbitmaps); ++ /* Compute the actual required size from per-glyph metrics instead ++ * of trusting the file's bitmapSizes[] value, which may be smaller ++ * than the actual data written by RepadBitmap. */ ++ sizepadbitmaps = 0; ++ for (i = 0; i < nbitmaps; i++) { ++ int w, h, glyphBytes; ++ metric = &metrics[i].metrics; ++ w = metric->rightSideBearing - metric->leftSideBearing; ++ h = metric->ascent + metric->descent; ++ glyphBytes = BYTES_PER_ROW(w, glyph) * h; ++ if (glyphBytes < 0 || (glyphBytes > 0 && sizepadbitmaps > INT_MAX - glyphBytes)) { ++ pcfError("pcfReadFont(): bitmap size overflow\n"); ++ goto Bail; ++ } ++ sizepadbitmaps += glyphBytes; ++ } ++ padbitmaps = malloc(sizepadbitmaps ? sizepadbitmaps : 1); + if (!padbitmaps) { + pcfError("pcfReadFont(): Couldn't allocate padbitmaps (%d)\n", sizepadbitmaps); + goto Bail; + } + new = 0; + for (i = 0; i < nbitmaps; i++) { ++ int srcGlyphBytes; ++ + old = offsets[i]; + metric = &metrics[i].metrics; ++ ++ /* Validate source offset and source glyph size against the ++ * source bitmap buffer to prevent out-of-bounds reads. */ ++ srcGlyphBytes = BYTES_PER_ROW( ++ metric->rightSideBearing - metric->leftSideBearing, ++ srcPad) * (metric->ascent + metric->descent); ++ if (old < 0 || old > sizebitmaps || ++ srcGlyphBytes < 0 || srcGlyphBytes > sizebitmaps - old) { ++ pcfError("pcfReadFont(): bitmap offset/size out of bounds\n"); ++ free(padbitmaps); ++ goto Bail; ++ } ++ + offsets[i] = new; + new += RepadBitmap(bitmaps + old, padbitmaps + new, +- PCF_GLYPH_PAD(format), glyph, ++ srcPad, glyph, + metric->rightSideBearing - metric->leftSideBearing, + metric->ascent + metric->descent); + } + free(bitmaps); + bitmaps = padbitmaps; ++ } else { ++ /* Validate offsets and full glyph extents against bitmap buffer */ ++ for (i = 0; i < nbitmaps; i++) { ++ int glyphBytes; ++ xCharInfo *metric = &metrics[i].metrics; ++ ++ glyphBytes = BYTES_PER_ROW( ++ metric->rightSideBearing - metric->leftSideBearing, ++ glyph) * (metric->ascent + metric->descent); ++ if (offsets[i] >= (CARD32)sizebitmaps || ++ glyphBytes < 0 || ++ glyphBytes > sizebitmaps - (int)offsets[i]) { ++ pcfError("pcfReadFont(): bitmap offset/size out of bounds " ++ "(offset %u, size %d, total %d)\n", ++ offsets[i], glyphBytes, sizebitmaps); ++ goto Bail; ++ } ++ } + } + for (i = 0; i < nbitmaps; i++) + metrics[i].bits = bitmaps + offsets[i]; +@@ -624,6 +673,10 @@ pcfReadFont(FontPtr pFont, FontFilePtr file, + if (IS_EOF(file)) goto Bail; + if (encodingOffset == 0xFFFF) { + pFont->info.allExist = FALSE; ++ } else if (encodingOffset >= nmetrics) { ++ pcfError("pcfReadFont(): encoding offset %d out of range (nmetrics=%d)\n", ++ encodingOffset, nmetrics); ++ goto Bail; + } else { + if(!encoding[SEGMENT_MAJOR(i)]) { + encoding[SEGMENT_MAJOR(i)]= +-- +2.43.0 + diff --git a/meta/recipes-graphics/xorg-lib/libxfont2_2.0.6.bb b/meta/recipes-graphics/xorg-lib/libxfont2_2.0.6.bb index 1a0eb42681..29e4d3298f 100644 --- a/meta/recipes-graphics/xorg-lib/libxfont2_2.0.6.bb +++ b/meta/recipes-graphics/xorg-lib/libxfont2_2.0.6.bb @@ -16,6 +16,7 @@ XORG_PN = "libXfont2" BBCLASSEXTEND = "native" SRC_URI += "file://CVE-2026-56001.patch \ + file://CVE-2026-56002.patch \ " SRC_URI[sha256sum] = "74ca20017eb0fb3f56d8d5e60685f560fc85e5ff3d84c61c4cb891e40c27aef4" -- 2.43.0
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