Now that we aren't so rigid about the length of the key being passed
in, we need to be a bit more rigorous about checking the length of
the actual data against the claimed length (a'la num_subauths field).
Check for the case where userspace sends us a seemingly valid key
with a num_subauths field that goes beyond the end of the array. If
that happens, return -EIO and invalidate the key.
Also change the other places where we check for malformed keys in this
code to invalidate the key as well.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/cifs/cifsacl.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
index 0c0a594..bd18723 100644
--- a/fs/cifs/cifsacl.c
+++ b/fs/cifs/cifsacl.c
@@ -197,6 +197,8 @@ id_to_sid(unsigned int cid, uint sidtype, struct cifs_sid *ssid)
{
int rc;
struct key *sidkey;
+ struct cifs_sid *ksid;
+ unsigned int ksid_size;
char desc[3 + 10 + 1]; /* 3 byte prefix + 10 bytes for value + NULL */
const struct cred *saved_cred;
@@ -217,15 +219,28 @@ id_to_sid(unsigned int cid, uint sidtype, struct cifs_sid *ssid)
rc = -EIO;
cFYI(1, "%s: Downcall contained malformed key "
"(datalen=%hu)", __func__, sidkey->datalen);
- goto out_key_put;
+ goto invalidate_key;
}
- cifs_copy_sid(ssid, (struct cifs_sid *)sidkey->payload.data);
+
+ ksid = (struct cifs_sid *)sidkey->payload.data;
+ ksid_size = CIFS_SID_BASE_SIZE + (ksid->num_subauth * sizeof(__le32));
+ if (ksid_size > sidkey->datalen) {
+ rc = -EIO;
+ cFYI(1, "%s: Downcall contained malformed key (datalen=%hu, "
+ "ksid_size=%u)", __func__, sidkey->datalen, ksid_size);
+ goto invalidate_key;
+ }
+ cifs_copy_sid(ssid, ksid);
key_set_timeout(sidkey, cifs_idmap_cache_timeout);
out_key_put:
key_put(sidkey);
out_revert_creds:
revert_creds(saved_cred);
return rc;
+
+invalidate_key:
+ key_invalidate(sidkey);
+ goto out_key_put;
}
static int
@@ -271,6 +286,7 @@ sid_to_id(struct cifs_sb_info *cifs_sb, struct cifs_sid *psid,
rc = -EIO;
cFYI(1, "%s: Downcall contained malformed key "
"(datalen=%hu)", __func__, sidkey->datalen);
+ key_invalidate(sidkey);
goto out_key_put;
}
--
1.7.11.7
--
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