From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Eric W. Biederman" Date: Mon, 06 Jun 2022 22:16:01 +0000 Subject: Re: [PATCH 08/16] ptrace: Only populate last_siginfo from ptrace Message-Id: <87pmjl1lr2.fsf@email.froward.int.ebiederm.org> List-Id: References: <871qwq5ucx.fsf_-_@email.froward.int.ebiederm.org> <20220518225355.784371-8-ebiederm@xmission.com> <20220524152725.GE14347@redhat.com> In-Reply-To: <20220524152725.GE14347@redhat.com> (Oleg Nesterov's message of "Tue, 24 May 2022 17:27:25 +0200") MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Oleg Nesterov Cc: linux-kernel@vger.kernel.org, rjw@rjwysocki.net, mingo@kernel.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de, bigeasy@linutronix.de, Will Deacon , tj@kernel.org, linux-pm@vger.kernel.org, Peter Zijlstra , Richard Weinberger , Anton Ivanov , Johannes Berg , linux-um@lists.infradead.org, Chris Zankel , Max Filippov , linux-xtensa@linux-xtensa.org, Kees Cook , Jann Horn , linux-ia64@vger.kernel.org, Robert OCallahan , Kyle Huey , Richard Henderson , Ivan Kokshaysky , Matt Turner , Jason Wessel , Daniel Thompson , Douglas Anderson , Douglas Miller , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras Oleg Nesterov writes: > On 05/18, Eric W. Biederman wrote: >> >> The code in ptrace_signal to populate siginfo if the signal number >> changed is buggy. If the tracer contined the tracee using >> ptrace_detach it is guaranteed to use the real_parent (or possibly a >> new tracer) but definitely not the origional tracer to populate si_pid >> and si_uid. > > I guess nobody cares. As the comment says > > If the debugger wanted something > specific in the siginfo structure then it should > have updated *info via PTRACE_SETSIGINFO. > > otherwise I don't think si_pid/si_uid have any value. No one has complained so it is clearly no one cares. So it is definitely not a regression. Or even anything that needs to be backported. However si_pid and si_uid are defined with SI_USER are defined to be whomever sent the signal. So I would argue by definition those values are wrong. > However the patch looks fine to me, just the word "buggy" looks a bit > too strong imo. I guess I am in general agreement. Perhaps I can just say they values are wrong by definition? Eric