udf_build_ustr was completely broken when
size >= UDF_NAME_LEN - 1 or size < 2

nobody noticed because all callers set size
to acceptable values (constants)

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Jan Kara <jack@suse.cz>
---
 fs/udf/unicode.c |   12 ++++++------
 1 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/udf/unicode.c b/fs/udf/unicode.c
index f969617..f4e54e5 100644
--- a/fs/udf/unicode.c
+++ b/fs/udf/unicode.c
@@ -47,16 +47,16 @@ static int udf_char_to_ustr(struct ustr *dest, const uint8_t *src, int strlen)
  */
 int udf_build_ustr(struct ustr *dest, dstring *ptr, int size)
 {
-	int usesize;
+	u8 usesize;
 
-	if ((!dest) || (!ptr) || (!size))
+	if (!dest || !ptr || size < 2)
 		return -1;
 
-	memset(dest, 0, sizeof(struct ustr));
-	usesize = (size > UDF_NAME_LEN) ? UDF_NAME_LEN : size;
+	usesize = min_t(size_t, size - 2, sizeof(dest->u_name));
 	dest->u_cmpID = ptr[0];
-	dest->u_len = ptr[size - 1];
-	memcpy(dest->u_name, ptr + 1, usesize - 1);
+	dest->u_len = usesize;
+	memcpy(dest->u_name, ptr + 1, usesize);
+	memset(dest->u_name + usesize, 0, sizeof(dest->u_name) - usesize);
 
 	return 0;
 }
-- 
1.5.3.7

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