Bug #833

memcpy of non-packed struct into packed struct (possible layout mismatch)

Added by Mathieu Desnoyers over 6 years ago. Updated almost 5 years ago.

Target version:
Start date:
Due date:
% Done:


Estimated time:


lttng-tools src/lib/lttng-ctl/lttng-ctl.c:


memcpy(&lsm.u.enable.event, ev, sizeof(lsm.u.enable.event));

copy "ev" (non-packed) into a packed structure.

We should copy each field one by one (create a copy_event_to_event_packed() helper to do so).


Updated by David Goulet over 6 years ago

  • Status changed from New to Feedback

How do you copy the union in the lttng_event field by field... ? That union contains non packed structure.


Updated by David Goulet over 6 years ago

  • Status changed from Feedback to Confirmed
  • Assignee deleted (David Goulet)

We need helper functions to copy field by field depending on the union type also.


Updated by Christian Babeux over 6 years ago

  • Target version set to 20

Updated by Christian Babeux about 6 years ago

  • Target version changed from 20 to 2.7

Updated by Michael Jeanson over 5 years ago

The "lttng_event" struct is not defined with the packed attribute, this attribute is only added when "lttng_event" is declared as a member of the "lttcomm_session_msg" struct. Adding the packed attribute to an already defined struct is ignored by the compiler, when it's done outside of a parent struct it generates a warning.

What this all means is that we are not copying a non-packed struct into a packed struct because there is no packed version of lttng_event. This also means we are using unpacked structures in the communication protocol between the client and the sessiond.


Updated by Jérémie Galarneau over 5 years ago

  • Target version changed from 2.7 to 2.8

Updated by Jérémie Galarneau almost 5 years ago

  • Target version changed from 2.8 to 2.9

Also available in: Atom PDF