From fbbd9f890959ef31878ecbe4c6b5b065aacd83a6 Mon Sep 17 00:00:00 2001
From: iefa m <iefa@research.itecz.au>
Date: Tue, 13 Oct 2026 18:18:19 +0530
Subject: [PATCH] rationalize_path: don't collapse an absolute path to the
 empty string

---
 plugins/sudoers/rationalize.c                           | 7 +++++++
 plugins/sudoers/regress/rationalize/check_rationalize.c | 4 ++++
 2 files changed, 11 insertions(+)

diff --git a/plugins/sudoers/rationalize.c b/plugins/sudoers/rationalize.c
index d2961133e5..190a2a98f0 100644
--- a/plugins/sudoers/rationalize.c
+++ b/plugins/sudoers/rationalize.c
@@ -52,6 +52,13 @@ rationalize_path(char *path, bool dotdot)
 
 		/* The size argument includes the terminating NUL byte. */
 		memmove(cp, ep, (size_t)(path_end - ep) + 1);
+
+		/* An absolute path must not collapse to the empty string. */
+		if (cp == path && *cp == '\0') {
+		    /* /. -> / */
+		    path[0] = '/';
+		    path[1] = '\0';
+		}
 		continue;
 	    }
 
diff --git a/plugins/sudoers/regress/rationalize/check_rationalize.c b/plugins/sudoers/regress/rationalize/check_rationalize.c
index 37a562e23f..34668c1825 100644
--- a/plugins/sudoers/regress/rationalize/check_rationalize.c
+++ b/plugins/sudoers/regress/rationalize/check_rationalize.c
@@ -54,6 +54,10 @@ static struct test_data rationalize_test_data[] = {
     { "/etc/../usr/lib", "/usr/lib" },		/* 19 */
     { "/etc/../usr/..", "/" },			/* 20 */
     { "/usr/lib/../../etc", "/etc" },		/* 21 */
+    { "/.", "/" },				/* 22 */
+    { "//.", "/" },				/* 23 */
+    { "/.//.", "/" },				/* 24 */
+    { "/usr/..//.", "/" },			/* 25 */
     { NULL }
 };