Commit a846a195 authored Mar 24, 2008 by Pavel Emelyanov Committed by Linus Torvalds Mar 24, 2008

bsd_acct: plain current->real_parent access is not always safe



This is minor, but dereferencing even current real_parent is not safe on debug
kernels, since the memory, this points to, can be unmapped - RCU protection is
required.

Besides, the tgid field is deprecated and is to be replaced with task_tgid_xxx
call (the 2nd patch), so RCU will be required anyway.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 4dd4b920

kernel/acct.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -482,7 +482,9 @@ static void do_acct_process(struct file *file)
		#endif
		#if ACCT_VERSION==3
		ac.ac_pid = current->tgid;
		ac.ac_ppid = current->real_parent->tgid;
		rcu_read_lock();
		ac.ac_ppid = rcu_dereference(current->real_parent)->tgid;
		rcu_read_unlock();
		#endif

		spin_lock_irq(&current->sighand->siglock);

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