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Commit a846a195 authored by Pavel Emelyanov's avatar Pavel Emelyanov Committed by Linus Torvalds
Browse files

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: default avatarPavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus 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);