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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>
This commit is contained in:
Jeff Layton 2012-12-03 06:05:31 -05:00 committed by Steve French
parent 7ee0b4c635
commit 1f6306806c
1 changed files with 12 additions and 3 deletions
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15
fs/cifs/cifsacl.c
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@ -57,7 +57,7 @@ cifs_idmap_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
* 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 @@ cifs_idmap_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
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 @@ id_to_sid(unsigned int cid, uint sidtype, struct cifs_sid *ssid)
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 @@ id_to_sid(unsigned int cid, uint sidtype, struct cifs_sid *ssid)
"ksid_size=%u)", __func__, sidkey->datalen, ksid_size);
goto invalidate_key;
}
cifs_copy_sid(ssid, ksid);
out_key_put:
key_put(sidkey);