From bee65149cc025522ae0e2c37a0ce817641ebac28 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Mon, 4 Nov 2019 18:43:49 -0500
Subject: [PATCH 02/10] libext2fs: fix UBSan when updating an inline_data file

What memcpy does when the length is zero is not well-defined.  So
avoid it.

Bug: https://github.com/tytso/e2fsprogs/issues/25
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 lib/ext2fs/ext_attr.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/ext2fs/ext_attr.c b/lib/ext2fs/ext_attr.c
index 78a823a9..affc1a8f 100644
--- a/lib/ext2fs/ext_attr.c
+++ b/lib/ext2fs/ext_attr.c
@@ -1550,14 +1550,15 @@ errcode_t ext2fs_xattr_set(struct ext2_xattr_handle *h,
 						       new_value, &value_len);
 		if (ret)
 			goto out;
-	} else
+	} else if (value_len)
 		memcpy(new_value, value, value_len);
 
 	/* Imitate kernel behavior by skipping update if value is the same. */
 	for (x = h->attrs; x < h->attrs + h->count; x++) {
 		if (!strcmp(x->name, name)) {
 			if (!x->ea_ino && x->value_len == value_len &&
-			    !memcmp(x->value, new_value, value_len)) {
+			    (!value_len ||
+			     !memcmp(x->value, new_value, value_len))) {
 				ret = 0;
 				goto out;
 			}
-- 
2.21.1