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SubjectRe: [PATCH]Fix the order of atomic operations in restore_previous_kprobes on ia64
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On Sat, 2008-01-19 at 00:20 +0800, Masami Hiramatsu wrote:
> From: Masami Hiramatsu <mhiramat@redhat.com>
>
> Fix the order of atomic operations to prevent overwriting
> prev_kprobe[0].
> To pop values from stack, we must decrement stack index right AFTER
> reading values.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
> ---
> Details of this issue was reported to
> http://sources.redhat.com/bugzilla/show_bug.cgi?id=2071
>
> arch/ia64/kernel/kprobes.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> Index: 2.6.24-rc8/arch/ia64/kernel/kprobes.c
> ===================================================================
> --- 2.6.24-rc8.orig/arch/ia64/kernel/kprobes.c 2008-01-17
> 21:14:01.000000000 -0500
> +++ 2.6.24-rc8/arch/ia64/kernel/kprobes.c 2008-01-17
> 21:14:01.000000000 -0500
> @@ -381,9 +381,10 @@
> static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk
> *kcb)
> {
> unsigned int i;
> - i = atomic_sub_return(1, &kcb->prev_kprobe_index);
> - __get_cpu_var(current_kprobe) = kcb->prev_kprobe[i].kp;
> - kcb->kprobe_status = kcb->prev_kprobe[i].status;
> + i = atomic_read(&kcb->prev_kprobe_index);
> + __get_cpu_var(current_kprobe) = kcb->prev_kprobe[i-1].kp;
> + kcb->kprobe_status = kcb->prev_kprobe[i-1].status;
> + atomic_sub(1, &kcb->prev_kprobe_index);
> }
>
> static void __kprobes set_current_kprobe(struct kprobe *p,
Acked. Thanks for the patch.

Thanks,
Shaohua



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