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[73.140.212.29]) by smtp.gmail.com with ESMTPSA id u8sm14684681pfl.16.2019.02.02.02.04.41 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sat, 02 Feb 2019 02:04:42 -0800 (PST) Date: Sat, 2 Feb 2019 02:04:40 -0800 From: Andrei Vagin To: Andrew Morton Cc: Oleg Nesterov , linux-kernel@vger.kernel.org, "Eric W. Biederman" Subject: Re: [PATCH] ptrace: take into account saved_sigmask in PTRACE_{GET,SET}SIGMASK Message-ID: <20190202100439.GA16265@gmail.com> References: <20181120060616.6043-1-avagin@gmail.com> <20181121181650.8d2d6abcf83b9defb7195cd3@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=koi8-r Content-Disposition: inline In-Reply-To: <20181121181650.8d2d6abcf83b9defb7195cd3@linux-foundation.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 21, 2018 at 06:16:50PM -0800, Andrew Morton wrote: > On Mon, 19 Nov 2018 22:06:16 -0800 Andrei Vagin wrote: > > > There are a few system calls (pselect, ppoll, etc) which replace a task > > sigmask while they are running in a kernel-space > > > > When a task calls one of these syscalls, the kernel saves a current > > sigmask in task->saved_sigmask and sets a syscall sigmask. > > > > On syscall-exit-stop, ptrace traps a task before restoring the > > saved_sigmask, so PTRACE_GETSIGMASK returns the syscall sigmask and > > PTRACE_SETSIGMASK does nothing, because its sigmask is replaced by > > saved_sigmask, when the task returns to user-space. > > > > This patch fixes this problem. PTRACE_GET_SIGMASK returns saved_sigmask > > is it's set. PTRACE_SETSIGMASK drops the TIF_RESTORE_SIGMASK flag. > > Looks good to me, but what would I know. I'll await input from Eric > and/or Oleg (please). Hi Andrew, What is your plan for this patch? In the ~akpm/mmotm/series, I see a comment of waiting for ack from Oleg. Here was a feedback from Oleg: https://www.spinics.net/lists/kernel/msg2972154.html where he said: "Ok, I think the patch is fine". Is it enough or should I convince him to send a "real" ack? Thanks, Andrei > > > --- a/include/linux/sched/signal.h > > +++ b/include/linux/sched/signal.h > > @@ -417,10 +417,20 @@ static inline void set_restore_sigmask(void) > > set_thread_flag(TIF_RESTORE_SIGMASK); > > WARN_ON(!test_thread_flag(TIF_SIGPENDING)); > > } > > + > > +static inline void clear_tsk_restore_sigmask(struct task_struct *tsk) > > +{ > > + clear_tsk_thread_flag(tsk, TIF_RESTORE_SIGMASK); > > +} > > How irritating is it that this file uses "task" 85 times and "tsk" 19 > times? What did that gain us? This patch worsens things. > > Oh well.