Quote from kern/37573:
There is an obvious race in netinet/ip_dummynet.c:config_pipe().
Interrupts are not blocked when changing the params of an
existing pipe. The specific crash observed:
... -> config_pipe -> set_fs_parms -> config_red
malloc a new w_q_lookup table but take an interrupt before
intializing it, interrupt handler does:
... -> dummynet_io -> red_drops
red_drops dereferences the uninitialized (zeroed) w_q_lookup
table.
o Flush accumulated credits for idle pipes.
o Flush accumulated credits when change pipe characteristics.
o Change dn_flow_queue.numbytes type to unsigned long.
Overlapping dn_flow_queue->numbytes in ready_event() leads to
numbytes becomes negative and SET_TICKS() macro returns a very
big value. heap_insert() overlaps dn_key again and inserts a
queue to a ready heap with a sched_time points to the past.
That leads to an "infinity" loop.
PR: kern/33234, kern/37573, misc/42459, kern/43133,
kern/44045, kern/48099
Submitted by: Mike Hibler <mike@cs.utah.edu> (kern/37573)
MFC after: 6 weeks
be1e4c5162