Messages in this thread Patch in this message | | | Date | Mon, 17 Mar 2008 13:48:29 +0300 | From | Pavel Emelyanov <> | Subject | [PATCH 1/2] Bsd_acct: plain current->real_parent access is not always safe |
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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>
--- kernel/acct.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/kernel/acct.c b/kernel/acct.c index 521dfa5..7ff5339 100644 --- a/kernel/acct.c +++ b/kernel/acct.c @@ -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(¤t->sighand->siglock); -- 1.5.3.4
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