From: Ankur Tyagi <[email protected]> Debian[1] also identified the fix.
[1]https://security-tracker.debian.org/tracker/CVE-2026-59679 Signed-off-by: Ankur Tyagi <[email protected]> --- .../xorg-lib/libxfont2/CVE-2026-59679.patch | 93 +++++++++++++++++++ .../xorg-lib/libxfont2_2.0.7.bb | 1 + 2 files changed, 94 insertions(+) create mode 100644 meta/recipes-graphics/xorg-lib/libxfont2/CVE-2026-59679.patch diff --git a/meta/recipes-graphics/xorg-lib/libxfont2/CVE-2026-59679.patch b/meta/recipes-graphics/xorg-lib/libxfont2/CVE-2026-59679.patch new file mode 100644 index 0000000000..8e2ea4bd62 --- /dev/null +++ b/meta/recipes-graphics/xorg-lib/libxfont2/CVE-2026-59679.patch @@ -0,0 +1,93 @@ +From 016a21b1eea8e4aef4949e19cdf5f386f36fd978 Mon Sep 17 00:00:00 2001 +From: Peter Hutterer <[email protected]> +Date: Mon, 13 Jul 2026 15:48:06 +1000 +Subject: [PATCH] fserve: validate num_chars against encoding array size in + fs_read_glyphs + +FS_QueryXExtents16 causes us to allocate the encoding[] array, later +during the FS_QueryXBitmaps16 reply handling we fill in that array. +There is no verification that the allocation is large enough, a +malicious font server could send us a small numExtents and a +large num_chars to force underallocation and OOB read/rwrite. + +A regression test is included that constructs a crafted +FS_QueryXBitmaps16 reply with num_chars > num_encoding and verifies +the library rejects it. + +CVE-2026-59679 + +Found-by: Zhixi "Jace" Sun, independent security researcher +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/36> + +CVE: CVE-2026-59679 +Upstream-Status: Backport [https://gitlab.freedesktop.org/xorg/lib/libxfont/-/commit/668fea81f40bcb48ec67fb55d0b851049d265290] + +Dropped makefile and test changes during backport. + +Signed-off-by: Ankur Tyagi <[email protected]> +--- + src/fc/fserve.c | 22 ++++++++++++++++++++++ + src/fc/fservestr.h | 1 + + 2 files changed, 23 insertions(+) + +diff --git a/src/fc/fserve.c b/src/fc/fserve.c +index abf7d07..744a68c 100644 +--- a/src/fc/fserve.c ++++ b/src/fc/fserve.c +@@ -1081,6 +1081,7 @@ fs_read_extent_info(FontPathElementPtr fpe, FSBlockDataPtr blockrec) + return AllocError; + } + fsfont->encoding = pCI; ++ fsfont->num_encoding = numExtents; + if (haveInk) + fsfont->inkMetrics = pCI + numExtents; + else +@@ -1980,6 +1981,17 @@ fs_read_glyphs(FontPathElementPtr fpe, FSBlockDataPtr blockrec) + { + minchar = 0; + maxchar = rep->num_chars; ++ ++ /* Reject replies where num_chars exceeds the encoding array ++ size allocated in fs_read_extent_info() to prevent ++ out-of-bounds access on encoding[]. */ ++ if (rep->num_chars > (CARD32)fsdata->num_encoding) ++ { ++ ErrorF("fserve: num_chars (%u) > num_encoding (%d)\n", ++ (unsigned) rep->num_chars, fsdata->num_encoding); ++ err = AllocError; ++ goto bail; ++ } + } + + off_adr = (char *)ppbits; +@@ -2001,6 +2013,16 @@ fs_read_glyphs(FontPathElementPtr fpe, FSBlockDataPtr blockrec) + for (i = 0; i < rep->num_chars; i++) + { + memcpy(&local_off, off_adr, SIZEOF(fsOffset32)); /* align it */ ++ /* Bounds-check minchar against the encoding array size to ++ prevent out-of-bounds access from a malicious font server ++ reply with more num_chars than num_extents. */ ++ if (minchar >= (unsigned long)fsdata->num_encoding) ++ { ++ ErrorF("fserve: glyph index %lu >= num_encoding (%d)\n", ++ minchar, fsdata->num_encoding); ++ err = AllocError; ++ goto bail; ++ } + if (blockrec->type == FS_OPEN_FONT || + fsdata->encoding[minchar].bits == &_fs_glyph_requested) + { +diff --git a/src/fc/fservestr.h b/src/fc/fservestr.h +index 29ae46e..da95e41 100644 +--- a/src/fc/fservestr.h ++++ b/src/fc/fservestr.h +@@ -43,6 +43,7 @@ typedef struct _fs_glyph { + typedef struct _fs_font { + CharInfoPtr pDefault; + CharInfoPtr encoding; ++ int num_encoding; + CharInfoPtr inkMetrics; + FSGlyphPtr glyphs; + } FSFontRec, *FSFontPtr; diff --git a/meta/recipes-graphics/xorg-lib/libxfont2_2.0.7.bb b/meta/recipes-graphics/xorg-lib/libxfont2_2.0.7.bb index de6418b11a..8775d1cc13 100644 --- a/meta/recipes-graphics/xorg-lib/libxfont2_2.0.7.bb +++ b/meta/recipes-graphics/xorg-lib/libxfont2_2.0.7.bb @@ -18,6 +18,7 @@ BBCLASSEXTEND = "native" SRC_URI += "file://CVE-2026-56001.patch \ file://CVE-2026-56002.patch \ file://CVE-2026-56003.patch \ + file://CVE-2026-59679.patch \ " SRC_URI[sha256sum] = "8b7b82fdeba48769b69433e8e3fbb984a5f6bf368b0d5f47abeec49de3e58efb"
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