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User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.7.2) Gecko/20040803

Description of problem:
In certain cases, proc_pid_stat() can dereference an invalid ->real_parent if the task is in the TASK_DEAD state.  The same problem had existed in task_state(), but was fixed by calling pid_alive() to see if the task was alive or not before dereferencing any of the task's pointer fields.  A similar fix should go into proc_pid_stat().

This same problem was also reported to lkml here:

http://marc.theaimsgroup.com/?l=linux-kernel&m=110246758508105&w=2

and was fixed in the 2.6.11 kernel.



Version-Release number of selected component (if applicable):


How reproducible:
Sometimes

Steps to Reproduce:
1. Run any program that will read /proc task entries (eg. top, ps)
2. Start various processes that exit (or can be killed) while top, ps, etc. is
   running.  In some cases, proc_pid_stat() will deal with a task that is marked 
   TASK_DEAD, and dereferencing ->real_parent will cause an oops.
  

Additional info: