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Subject[PATCH] ptrace: locked accesss to ptrace last_siginfo


ptrace_setsiginfo/ptrace_getsiginfo need to do locked access
to last_siginfo. ptrace_notify()/ptrace_stop() sets the
current->last_siginfo and sleeps on schedule(). It can be waked
up by kill signal from signal_wake_up before debugger wakes it up.
On return from schedule(), the current->last_siginfo is reset.

Signed-off-by: Prasanna Meda <pmeda@akamai.com>


--- a/kernel/ptrace.c Fri Nov 19 18:27:26 2004
+++ b/kernel/ptrace.c Fri Nov 19 18:52:52 2004
@@ -303,18 +303,33 @@

static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data)
{
- if (child->last_siginfo == NULL)
- return -EINVAL;
- return copy_siginfo_to_user(data, child->last_siginfo);
+ siginfo_t lastinfo;
+
+ spin_lock_irq(&child->sighand->siglock);
+ if (likely(child->last_siginfo != NULL)) {
+ memcpy(&lastinfo, child->last_siginfo, sizeof (siginfo_t));
+ spin_unlock_irq(&child->sighand->siglock);
+ return copy_siginfo_to_user(data, &lastinfo);
+ }
+ spin_unlock_irq(&child->sighand->siglock);
+ return -EINVAL;
}

static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data)
{
- if (child->last_siginfo == NULL)
- return -EINVAL;
- if (copy_from_user(child->last_siginfo, data, sizeof (siginfo_t)) != 0)
+ siginfo_t newinfo;
+
+ if (copy_from_user(&newinfo, data, sizeof (siginfo_t)) != 0)
return -EFAULT;
- return 0;
+
+ spin_lock_irq(&child->sighand->siglock);
+ if (likely(child->last_siginfo != NULL)) {
+ memcpy(child->last_siginfo, &newinfo, sizeof (siginfo_t));
+ spin_unlock_irq(&child->sighand->siglock);
+ return 0;
+ }
+ spin_unlock_irq(&child->sighand->siglock);
+ return -EINVAL;
}

int ptrace_request(struct task_struct *child, long request,
-
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