[PATCH] fix copy_sighand() vs do_sigaction() race

[Oleg Nesterov]

copy_sighand() should hold ->sighand->siglock while copying
->sighand->action, another thread may be doing sigaction().

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>

--- RC-1/kernel/fork.c~	2006-02-07 01:41:14.000000000 +0300
+++ RC-1/kernel/fork.c	2006-02-08 23:38:56.000000000 +0300
@@ -766,7 +766,9 @@ static inline int copy_sighand(unsigned 
 		return -ENOMEM;
 	spin_lock_init(&sig->siglock);
 	atomic_set(&sig->count, 1);
+	spin_lock_irq(&current->sighand->siglock);
 	memcpy(sig->action, current->sighand->action, sizeof(sig->action));
+	spin_unlock_irq(&current->sighand->siglock);
 	return 0;
 }
-
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