udf: fix udf_build_ustr
udf_build_ustr was broken:
- size == 1:
dest->u_len = ptr[1 - 1], but at ptr[0] there's cmpID,
so we created string with wrong length
it should not happen, so we BUG() it
- size > 1 and size < UDF_NAME_LEN:
we set u_len correctly, but memcpy copied one needless byte
- size == UDF_NAME_LEN - 1:
memcpy overwrited u_len - with correct value, but...
- size >= UDF_NAME_LEN:
we copied UDF_NAME_LEN - 1 bytes, but dest->u_name is array
of UDF_NAME_LEN - 2 bytes, so we were overwriting u_len with
character from input string
nobody noticed because all callers set size
to acceptable values (constants within range)
Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/udf/unicode.c b/fs/udf/unicode.c
index 05bc505..24d6165 100644
--- a/fs/udf/unicode.c
+++ b/fs/udf/unicode.c
@@ -48,14 +48,16 @@
{
int usesize;
- if ((!dest) || (!ptr) || (!size))
+ if (!dest || !ptr || !size)
return -1;
+ BUG_ON(size < 2);
- memset(dest, 0, sizeof(struct ustr));
- usesize = (size > UDF_NAME_LEN) ? UDF_NAME_LEN : size;
+ usesize = min_t(size_t, ptr[size - 1], sizeof(dest->u_name));
+ usesize = min(usesize, size - 2);
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;
}