ksmbd: fix slub overflow in ksmbd_decode_ntlmssp_auth_blob()

If authblob->SessionKey.Length is bigger than session key
size(CIFS_KEY_SIZE), slub overflow can happen in key exchange codes.
cifs_arc4_crypt copy to session key array from SessionKey from client.

Cc: stable@vger.kernel.org
Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-21940
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/server/auth.c b/fs/smb/server/auth.c
index af7b2cd..229a652 100644 (file)
--- a/fs/smb/server/auth.c
+++ b/fs/smb/server/auth.c
@@ -355,6 +355,9 @@ int ksmbd_decode_ntlmssp_auth_blob(struct authenticate_message *authblob,
                if (blob_len < (u64)sess_key_off + sess_key_len)
                        return -EINVAL;
 
+               if (sess_key_len > CIFS_KEY_SIZE)
+                       return -EINVAL;
+
                ctx_arc4 = kmalloc(sizeof(*ctx_arc4), GFP_KERNEL);
                if (!ctx_arc4)
                        return -ENOMEM;