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greybus: short message is OK for errors

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We enforce a rule that a response message must completely fill the
buffer that's been allocated to hold it.  However, if an error
occurs, the payload is off limits, so we should allow a short
message to convey an error result.

Change gb_connection_recv_response() to require the right message
size only if there's no error.

One other thing:  The arriving data is only being copied into the
response buffer if the request was successful.  That means the
response message header is assumed to have been initialized.  That
isn't a valid assumption.  So change it so that if an error is
seen, the header portion of the message is copied into the
response buffer--but only the header.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
This commit is contained in:
Alex Elder 2014-12-02 08:30:29 -06:00 • committed by Greg Kroah-Hartman
parent 34db1f91e6
commit f71e1cc194
1 changed files with 5 additions and 8 deletions
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13
drivers/staging/greybus/operation.c
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@ -655,7 +655,6 @@ static void gb_connection_recv_response(struct gb_connection *connection,
{
struct gb_operation *operation;
struct gb_message *message;
struct gb_operation_msg_hdr *header;
int result;
operation = gb_pending_operation_find(connection, operation_id);
@ -668,19 +667,17 @@ static void gb_connection_recv_response(struct gb_connection *connection,
gb_pending_operation_remove(operation);
message = operation->response;
if (size == message->size) {
/* Transfer the operation result from the response header */
header = message->header;
result = gb_operation_status_map(header->result);
} else {
result = gb_operation_status_map(message->header->result);
if (!result && size != message->size) {
gb_connection_err(connection, "bad message size (%zu != %zu)",
size, message->size);
result = -EMSGSIZE;
}
/* We must ignore the payload if a bad status is returned */
if (!result)
memcpy(message->header, data, size);
if (result)
size = sizeof(*message->header);
memcpy(message->header, data, size);
/* The rest will be handled in work queue context */
if (gb_operation_result_set(operation, result))