[S390] cio: fix potential overflow in chpid descriptor

The length filed in the chsc response block (if valid)
has a value of n*(sizeof(chp_desc))+8 (for the response
block header). When we memcopied from the response block
to the actual descriptor we copied 8 bytes too much.
The bug was not revealed since the descriptor is embedded
in struct channel_path.
Since we only write one descriptor at a time ignore the
length value and use sizeof(*desc).

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/drivers/s390/cio/chsc.c b/drivers/s390/cio/chsc.c
index ce7cb87479fe3b8aed786eeea182549da7352b35..407d0e9adfaf96a0d4362f8e56c986f0c17700fa 100644 (file)
--- a/drivers/s390/cio/chsc.c
+++ b/drivers/s390/cio/chsc.c
@@ -713,7 +713,7 @@ int chsc_determine_base_channel_path_desc(struct chp_id chpid,
        ret = chsc_determine_channel_path_desc(chpid, 0, 0, 0, 0, chsc_resp);
        if (ret)
                goto out_free;
-       memcpy(desc, &chsc_resp->data, chsc_resp->length);
+       memcpy(desc, &chsc_resp->data, sizeof(*desc));
 out_free:
        kfree(chsc_resp);
        return ret;