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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2009-06-19 17:39:33 +0200
committerIngo Molnar <mingo@elte.hu>2009-06-19 17:57:36 +0200
commitb49a9e7e72103ea91946453c19703a4dfa1994fe (patch)
tree7e9e74881384c581afca56cc397901f71e904c8b /tools/perf/builtin-stat.c
parent0c87197142427063e096f11603543ca874045952 (diff)
perf_counter: Close race in perf_lock_task_context()
perf_lock_task_context() is buggy because it can return a dead context. the RCU read lock in perf_lock_task_context() only guarantees the memory won't get freed, it doesn't guarantee the object is valid (in our case refcount > 0). Therefore we can return a locked object that can get freed the moment we release the rcu read lock. perf_pin_task_context() then increases the refcount and does an unlock on freed memory. That increased refcount will cause a double free, in case it started out with 0. Ammend this by including the get_ctx() functionality in perf_lock_task_context() (all users already did this later anyway), and return a NULL context when the found one is already dead. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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