Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Richard Hill reported an occasional NULL pointer deference in port_delay_request() when in hybrid mode. if (p->hybrid_e2e) { struct ptp_message *dst = TAILQ_FIRST(&p->best->messages); msg->address = dst->address; ... } The code assumes that the p->best->messages list can't be empty because: The function, port_delay_request(), is called only when FD_DELAY_TIMER expires. That timer is only set by the function, port_set_delay_tmo(), which is called: 1. from process_delay_resp(), but only when state is UNCALIBRATED or SLAVE. 2. from port_e2e_transition(), but only when state is UNCALIBRATED or SLAVE. Looking at handle_state_decision_event(), a port can only enter UNCALIBRATED or SLAVE when it has a valid foreign master record, ie p->best->messages is not null. A port also only clears p->best->messages when it leaves UNCALIBRATED or SLAVE, at which point the FD_DELAY_TIMER is also cleared. *However* the p->best->messages list *can* be empty if the FD_ANNOUNCE_TIMER and the FD_DELAY_TIMER expire at the same time. In this case, the poll() call indicates events on both file descriptors. The announce timeout is handled like this: case FD_ANNOUNCE_TIMER: case FD_SYNC_RX_TIMER: if (p->best) fc_clear(p->best); So then the port_delay_request() call de-references the null TAILQ_FIRST message pointer. This patch fixes the issue by re-ordering the timer file descriptors within the polling list. Signed-off-by: Richard Cochran <[email protected]> Reported-by: Richard Hill <[email protected]>
- Loading branch information