From c74f6f85eda50632c105f1fdb6308c90fdac8c46 Mon Sep 17 00:00:00 2001
From: Tobias Hunger <tobias.hunger@gmail.com>
Date: Fri, 25 Sep 2026 12:00:28 +0200
Subject: [PATCH] fix(xattr): Handle labels without value

I stumbled over this with the very first image I tried:

> sudo systemd-pull oci --system quay.io/toolbx/arch-toolbox:latest

That failed with a label "user.overlay.origin" with a value of NULL and size 0.

This one-line change allows value == NULL if size == 0 when setting xattrs.

(cherry picked from commit 885fe07ee37cff7316680b5088d11081e01813b1)
---
 src/basic/xattr-util.c     | 2 +-
 src/test/test-xattr-util.c | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/basic/xattr-util.c b/src/basic/xattr-util.c
index 417e8650e5..6128b1b68d 100644
--- a/src/basic/xattr-util.c
+++ b/src/basic/xattr-util.c
@@ -295,7 +295,7 @@ int xsetxattr_full(
         assert(fd >= 0 || fd == AT_FDCWD);
         assert((at_flags & ~(AT_SYMLINK_FOLLOW|AT_EMPTY_PATH)) == 0);
         assert(name);
-        assert(value);
+        assert(value || size == 0);
 
         if (size == SIZE_MAX)
                 size = strlen(value);
diff --git a/src/test/test-xattr-util.c b/src/test/test-xattr-util.c
index 4d39a0a1f1..5dda7be696 100644
--- a/src/test/test-xattr-util.c
+++ b/src/test/test-xattr-util.c
@@ -159,6 +159,10 @@ TEST(xsetxattr) {
         ASSERT_OK(xsetxattr_full(dfd, "test", 0, "user.foo", "dirfd", SIZE_MAX, XATTR_REPLACE));
         verify_xattr(dfd, "dirfd");
 
+        /* Empty xattr values are allowed */
+        ASSERT_OK(xsetxattr_full(dfd, "test", 0, "user.foo", NULL, 0, 0));
+        verify_xattr(dfd, "");
+
         /* by fd (O_PATH) */
         ASSERT_OK_ERRNO(fd = openat(dfd, "test", O_PATH|O_CLOEXEC));