Re: [PATCH 4.4.y] arm: kprobes: Allow to handle reentered kprobe on single-stepping

[Greg KH]

On Fri, Jul 09, 2021 at 10:46:30AM +0800, Shaobo Huang wrote:
> From: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> 
> commit f3fbd7ec62dec1528fb8044034e2885f2b257941 upstream
> 
> This is arm port of commit 6a5022a56ac3 ("kprobes/x86: Allow to
> handle reentered kprobe on single-stepping")
> 
> Since the FIQ handlers can interrupt in the single stepping
> (or preparing the single stepping, do_debug etc.), we should
> consider a kprobe is hit in the NMI handler. Even in that
> case, the kprobe is allowed to be reentered as same as the
> kprobes hit in kprobe handlers
> (KPROBE_HIT_ACTIVE or KPROBE_HIT_SSDONE).
> 
> The real issue will happen when a kprobe hit while another
> reentered kprobe is processing (KPROBE_REENTER), because
> we already consumed a saved-area for the previous kprobe.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> Signed-off-by: Jon Medhurst <tixy@xxxxxxxxxx>
> Fixes: 24ba613c9d6c ("ARM kprobes: core code")
> Cc: stable@xxxxxxxxxxxxxxx #v2.6.25~v4.11
> Signed-off-by: huangshaobo <huangshaobo6@xxxxxxxxxx>
> ---
>  arch/arm/probes/kprobes/core.c | 6 ++++++
>  1 file changed, 6 insertions(+)

Now queued up, thanks.

greg k-h