From 681ec1174d3bd3007aba8d22d014263ddce72b00 Mon Sep 17 00:00:00 2001
From: Andras Schmelczer <andras@schmelczer.dev>
Date: Tue, 27 Oct 2026 19:52:12 +0000
Subject: [PATCH] Enforce canonical LaTeX input directory boundaries

---
 .../external/pylatexenc/latex2text/__init__.py | 15 ++++++++++-----
 tests/utilities/test_latex_regressions.py      | 18 ++++++++++++++++++
 2 files changed, 28 insertions(+), 5 deletions(-)
 create mode 100644 tests/utilities/test_latex_regressions.py

diff --git a/great_ai/utilities/external/pylatexenc/latex2text/__init__.py b/great_ai/utilities/external/pylatexenc/latex2text/__init__.py
index 41b23b0..54360d1 100644
--- a/great_ai/utilities/external/pylatexenc/latex2text/__init__.py
+++ b/great_ai/utilities/external/pylatexenc/latex2text/__init__.py
@@ -974,11 +974,20 @@ class LatexNodes2Text(object):
             return ""
 
         fnfull = os.path.realpath(os.path.join(self.tex_input_directory, fn))
+        if not os.path.exists(fnfull) and os.path.exists(fnfull + ".tex"):
+            fnfull = fnfull + ".tex"
+        if not os.path.exists(fnfull) and os.path.exists(fnfull + ".latex"):
+            fnfull = fnfull + ".latex"
+        fnfull = os.path.realpath(fnfull)
         if self.strict_input:
             # make sure that the input file is strictly within dirfull, and
             # didn't escape with '../..' tricks or via symlinks.
             dirfull = os.path.realpath(self.tex_input_directory)
-            if not fnfull.startswith(dirfull):
+            try:
+                within_directory = os.path.commonpath([fnfull, dirfull]) == dirfull
+            except ValueError:  # paths on different Windows drives
+                within_directory = False
+            if not within_directory:
                 logger.warning(
                     "Can't access path '%s' leading outside of mandated directory "
                     "[strict input mode]",
@@ -986,10 +995,6 @@ class LatexNodes2Text(object):
                 )
                 return ""
 
-        if not os.path.exists(fnfull) and os.path.exists(fnfull + ".tex"):
-            fnfull = fnfull + ".tex"
-        if not os.path.exists(fnfull) and os.path.exists(fnfull + ".latex"):
-            fnfull = fnfull + ".latex"
         if not os.path.isfile(fnfull):
             logger.warning("Error, file doesn't exist: '%s'", fn)
             return ""
diff --git a/tests/utilities/test_latex_regressions.py b/tests/utilities/test_latex_regressions.py
new file mode 100644
index 0000000..3dfe0ca
--- /dev/null
+++ b/tests/utilities/test_latex_regressions.py
@@ -0,0 +1,18 @@
+from pathlib import Path
+
+from great_ai.utilities.external.pylatexenc.latex2text import LatexNodes2Text
+
+
+def test_strict_input_checks_path_ancestry(tmp_path: Path) -> None:
+    allowed = tmp_path / "allowed"
+    sibling = tmp_path / "allowed_neighbor"
+    allowed.mkdir()
+    sibling.mkdir()
+    (allowed / "inside.tex").write_text("inside")
+    (sibling / "outside.tex").write_text("outside")
+    (allowed / "link.tex").symlink_to(sibling / "outside.tex")
+    converter = LatexNodes2Text()
+    converter.set_tex_input_directory(str(allowed), strict_input=True)
+    assert converter.latex_to_text(r"\input{inside}") == "inside"
+    assert converter.latex_to_text(r"\input{../allowed_neighbor/outside}") == ""
+    assert converter.latex_to_text(r"\input{link}") == ""