[PATCH] hfsplus: fix truncated xattr names in listxattr()

[Maurycy Pawlowski-Wieronski via B4 Relay]

From: Maurycy Pawlowski-Wieronski <maurycy@xxxxxxxxxxx>

Commit 7dcbf17e3f91 ("hfsplus: refactor copy_name to not use strncpy")
changed copy_name() to build names in the osx. namespace with
scnprintf().

The supplied buffer size includes room for the prefix and the name, but
not for the terminating NUL:

  $ python3 -c "import os; print(os.listxattr('/mnt/tm/.DS_Store'))"
  ['osx.com.apple.FinderInf']

The truncated names cannot be passed back to getxattr(), so getfattr -d,
rsync -X, cp --preserve=xattr and tar --xattrs etc. seem to lose all
Apple attributes on hfsplus volumes.

Names in other namespaces go through the strscpy() branch, which already
sizes the buffer correctly. That's `why xfstests generic/377 does not
catch it.

Fixes: 7dcbf17e3f91 ("hfsplus: refactor copy_name to not use strncpy")
Cc: stable@xxxxxxxxxxxxxxx # v6.10+
Signed-off-by: Maurycy Pawlowski-Wieronski <maurycy@xxxxxxxxxxx>
---
 fs/hfsplus/xattr.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/hfsplus/xattr.c b/fs/hfsplus/xattr.c
index 21a1c196c71f..4a3c97373682 100644
--- a/fs/hfsplus/xattr.c
+++ b/fs/hfsplus/xattr.c
@@ -515,8 +515,8 @@ static ssize_t copy_name(char *buffer, const char *xattr_name, size_t name_len)
 	memset(buffer, 0, name_len);
 
 	if (!is_known_namespace(xattr_name)) {
-		len = scnprintf(buffer, name_len + XATTR_MAC_OSX_PREFIX_LEN,
-				 "%s%s", XATTR_MAC_OSX_PREFIX, xattr_name);
+		len = scnprintf(buffer, name_len + XATTR_MAC_OSX_PREFIX_LEN + 1,
+				"%s%s", XATTR_MAC_OSX_PREFIX, xattr_name);
 	} else {
 		len = strscpy(buffer, xattr_name, name_len + 1);
 		if (len < 0) {

---
base-commit: 1b78070aaef63512688aebfbc82365ef9d6660f1
change-id: 20260828-hfsplus-copy_name-fix-a6e2a0a4485e

Best regards,
--  
Maurycy Pawlowski-Wieronski <maurycy@xxxxxxxxxxx>