Sounds like formalizing this would be a good idea. Is there even one
counter-example that we can think of or that exists today?
Rob
Pete Wyckoff wrote:
[EMAIL PROTECTED] wrote on Thu, 19 Oct 2006 16:34 +0200:
We've plugged some similar bugs before by just fixing the specific case
(being more careful about cleaning up masks, pointers, sizes, etc. after
an error), and the same could easily be done here. Should there be a
more general solution, though?
What I am wondering is if the response encoder should even bother to
encode the whole message if the status is non-zero. It seems like if
there is an error code it should just stick to encoding the basic
PVFS_server_resp struct. The rest of the fields can't really be trusted
since we hit an error condition. Likewise on the decode side of things.
The lebf_encode_resp() function already sort of catches one case of this:
/* we stand a good chance of segfaulting if we try to encode the
response
* after something bad happened reading data from disk. */
if (resp->status != -PVFS_EIO)
{
... but that only handles one specific error code.
I'm sort of in agreement with your analysis. We had a similar issue
on the decoding side on the client: an EIO came back from the
server but the client proceeded to try to decode particular fields.
http://www.beowulf-underground.org/pipermail/pvfs2-developers/2006-June/002202.html
Maybe both the lebf_{en,de}code_resp should encode or decode the
rest of the message if status == 0. The comparison for EIO alone is
not sufficient.
Are there any reasons the client should be looking at more fields
once it sees a negative status? Maybe we should just formalize
this. And fixup lebf_decode_rel so it only frees things if status
was zero.
-- Pete
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