Re: [PATCH v3 1/4] rethook: use preempt_{disable, enable}_notrace in rethook_trampoline_handler

Masami Hiramatsu
2023-05-17T12:00:03Z

Hi Ze Gao,

On Wed, 17 May 2023 11:45:06 +0800
Ze Gao <zegao2021@gmail.com> wrote:

> This patch replaces preempt_{disable, enable} with its corresponding
> notrace version in rethook_trampoline_handler so no worries about stack
> recursion or overflow introduced by preempt_count_{add, sub} under
> fprobe + rethook context.
>
> Fixes: 54ecbe6f1ed5 ("rethook: Add a generic return hook")
> Signed-off-by: Ze Gao <zegao@tencent.com>
> Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> Cc: <stable@vger.kernel.org>
> Link: https://lore.kernel.org/linux-trace-kernel/20230516071830.8190-2-zegao@tencent.com

Note that you don't need to add Link tag of the previous version for each patch.
I'll add it when I pick it :)

Thank you,

> ---
> kernel/trace/rethook.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/trace/rethook.c b/kernel/trace/rethook.c
> index 32c3dfdb4d6a..60f6cb2b486b 100644
> --- a/kernel/trace/rethook.c
> +++ b/kernel/trace/rethook.c
> @@ -288,7 +288,7 @@ unsigned long rethook_trampoline_handler(struct pt_regs *regs,
> * These loops must be protected from rethook_free_rcu() because those
> * are accessing 'rhn->rethook'.
> */
> - preempt_disable();
> + preempt_disable_notrace();
>
> /*
> * Run the handler on the shadow stack. Do not unlink the list here because
> @@ -321,7 +321,7 @@ unsigned long rethook_trampoline_handler(struct pt_regs *regs,
> first = first->next;
> rethook_recycle(rhn);
> }
> - preempt_enable();
> + preempt_enable_notrace();
>
> return correct_ret_addr;
> }
> --
> 2.40.1
>

--
Masami Hiramatsu (Google) <mhiramat@kernel.org>