commit 9f339e7028e2855717af3193c938f9960ad13b38
author Markus Metzger <markus.t.metzger@intel.com> Wed Feb 11 15:10:27 2009 +0100
committer Ingo Molnar <mingo@elte.hu> Wed Feb 11 15:44:20 2009 +0100
tree 76e0e9181f4ee2b324742d517518e837d5c250bf
parent 06eb23b1ba39c61ee5d5faeb42a097635693e370

x86, ptrace, mm: fix double-free on race

Ptrace_detach() races with __ptrace_unlink() if the traced task is
reaped while detaching. This might cause a double-free of the BTS
buffer.

Change the ptrace_detach() path to only do the memory accounting in
ptrace_bts_detach() and leave the buffer free to ptrace_bts_untrace()
which will be called from __ptrace_unlink().

The fix follows a proposal from Oleg Nesterov.

Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>