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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id r23sm2773788pjo.3.2021.09.29.13.06.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Sep 2021 13:07:00 -0700 (PDT) Date: Wed, 29 Sep 2021 13:06:59 -0700 From: Kees Cook To: Dave Hansen Cc: Alexander Popov , Jonathan Corbet , Paul McKenney , Andrew Morton , Thomas Gleixner , Peter Zijlstra , Joerg Roedel , Maciej Rozycki , Muchun Song , Viresh Kumar , Robin Murphy , Randy Dunlap , Lu Baolu , Petr Mladek , Luis Chamberlain , Wei Liu , John Ogness , Andy Shevchenko , Alexey Kardashevskiy , Christophe Leroy , Jann Horn , Greg Kroah-Hartman , Mark Rutland , Andy Lutomirski , Dave Hansen , Steven Rostedt , Thomas Garnier , Will Deacon , Ard Biesheuvel , Laura Abbott , David S Miller , Borislav Petkov , kernel-hardening@lists.openwall.com, linux-hardening@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, notify@kernel.org Subject: Re: [PATCH] Introduce the pkill_on_warn boot parameter Message-ID: <202109291229.C64A1D9D@keescook> References: <20210929185823.499268-1-alex.popov@linux.com> <323d0784-249d-7fef-6c60-e8426d35b083@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <323d0784-249d-7fef-6c60-e8426d35b083@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 29, 2021 at 12:03:36PM -0700, Dave Hansen wrote: > On 9/29/21 11:58 AM, Alexander Popov wrote: > > --- a/kernel/panic.c > > +++ b/kernel/panic.c > > @@ -53,6 +53,7 @@ static int pause_on_oops_flag; > > static DEFINE_SPINLOCK(pause_on_oops_lock); > > bool crash_kexec_post_notifiers; > > int panic_on_warn __read_mostly; > > +int pkill_on_warn __read_mostly; I like this idea. I can't tell if Linus would tolerate it, though. But I really have wanted a middle ground like BUG(). Having only WARN() and panic() is not very friendly. :( > > unsigned long panic_on_taint; > > bool panic_on_taint_nousertaint = false; > > > > @@ -610,6 +611,9 @@ void __warn(const char *file, int line, void *caller, unsigned taint, > > > > print_oops_end_marker(); > > > > + if (pkill_on_warn && system_state >= SYSTEM_RUNNING) > > + do_group_exit(SIGKILL); > > + > > /* Just a warning, don't kill lockdep. */ > > add_taint(taint, LOCKDEP_STILL_OK); > > } > > Doesn't this tie into the warning *printing* code? That's better than > nothing, for sure. But, if we're doing this for hardening, I think we > would want to kill anyone provoking a warning, not just the first one > that triggered *printing* the warning. Right, this needs to be moved into the callers of __warn() (i.e. report_bug(), and warn_slowpath_fmt()), likely with some small refactoring in report_bug(). -- Kees Cook