[lwip-devel] [bug #19167] tcp timeout handler can cause crash being invoked by sys_sem_wait()

[goldsimon]

Follow-up Comment #14, bug #19167 (project lwip):

Hi Dimitry, 

regarding comment #8:

Please correct me if I'm wrong, but I tested your TIMESTAMP_DIFF() /
TIMESTAMP_ADD() suggestion, and I don't think it's a solution:

let's say time_now is 20 (=ms after time counting started) and we have a
timeout which is 4294967286 ms (e.g. nearly 50 days; I know it's unlikely,
but it's to show the wraparound).

If we now check like you proposed:
if(TIMESTAMP_DIFF(expires, now) > 0)
  wait()
else
  execute_timeout_handler_now()

we would execute the timeout handler, since (signed)(4294967286 - 20) = -10

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