cifs: deal with id_to_sid embedded sid reply corner case
A SID could potentially be embedded inside of payload.value if there are
no subauthorities, and the arch has 8 byte pointers. Allow for that
possibility there.
While we're at it, rephrase the "embedding" check in terms of
key->payload to allow for the possibility that the union might change
size in the future.
Reviewed-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
index 08b4d50..8dd9212 100644
--- a/fs/cifs/cifsacl.c
+++ b/fs/cifs/cifsacl.c
@@ -57,7 +57,7 @@
* With this however, you must check the datalen before trying to
* dereference payload.data!
*/
- if (prep->datalen <= sizeof(void *)) {
+ if (prep->datalen <= sizeof(key->payload)) {
key->payload.value = 0;
memcpy(&key->payload.value, prep->data, prep->datalen);
key->datalen = prep->datalen;
@@ -76,7 +76,7 @@
static inline void
cifs_idmap_key_destroy(struct key *key)
{
- if (key->datalen > sizeof(void *))
+ if (key->datalen > sizeof(key->payload))
kfree(key->payload.data);
}
@@ -216,7 +216,15 @@
goto invalidate_key;
}
- ksid = (struct cifs_sid *)sidkey->payload.data;
+ /*
+ * A sid is usually too large to be embedded in payload.value, but if
+ * there are no subauthorities and the host has 8-byte pointers, then
+ * it could be.
+ */
+ ksid = sidkey->datalen <= sizeof(sidkey->payload) ?
+ (struct cifs_sid *)&sidkey->payload.value :
+ (struct cifs_sid *)sidkey->payload.data;
+
ksid_size = CIFS_SID_BASE_SIZE + (ksid->num_subauth * sizeof(__le32));
if (ksid_size > sidkey->datalen) {
rc = -EIO;
@@ -224,6 +232,7 @@
"ksid_size=%u)", __func__, sidkey->datalen, ksid_size);
goto invalidate_key;
}
+
cifs_copy_sid(ssid, ksid);
out_key_put:
key_put(sidkey);