From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Kees Cook <keescook@chromium.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
PaX Team <pageexec@freemail.hu>, Jann Horn <jannh@google.com>,
Eric Biggers <ebiggers3@gmail.com>,
Christoph Hellwig <hch@infradead.org>,
"axboe@kernel.dk" <axboe@kernel.dk>,
James Bottomley <James.Bottomley@hansenpartnership.com>,
Elena Reshetova <elena.reshetova@intel.com>,
Hans Liljestrand <ishkamiel@gmail.com>,
David Windsor <dwindsor@gmail.com>,
"x86@kernel.org" <x86@kernel.org>, Ingo Molnar <mingo@kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"David S. Miller" <davem@davemloft.net>,
Rik van Riel <riel@redhat.com>,
linux-arch <linux-arch@vger.kernel.org>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>
Subject: Re: [PATCH v2 2/2] x86, refcount: Implement fast refcount overflow protection
Date: Mon, 1 May 2017 17:45:42 -0500 [thread overview]
Message-ID: <20170501224542.bbfhs7c4x2wibomz@treble> (raw)
In-Reply-To: <CAGXu5jKoeB7tbxfcLC03tFnjYKYt+ZHtk_jruQJ887dPHJ-Gag@mail.gmail.com>
On Mon, May 01, 2017 at 10:36:59AM -0700, Kees Cook wrote:
> >> +#ifdef CONFIG_FAST_REFCOUNT
> >> +static DEFINE_RATELIMIT_STATE(refcount_ratelimit, 15 * HZ, 3);
> >> +
> >> +void refcount_error_report(struct pt_regs *regs, const char *kind)
> >> +{
> >> + do_send_sig_info(SIGKILL, SEND_SIG_FORCED, current, true);
> >> +
> >> + if (!__ratelimit(&refcount_ratelimit))
> >> + return;
> >> +
> >> + pr_emerg("%s detected in: %s:%d, uid/euid: %u/%u\n",
> >> + kind ? kind : "refcount error",
> >> + current->comm, task_pid_nr(current),
> >> + from_kuid_munged(&init_user_ns, current_uid()),
> >> + from_kuid_munged(&init_user_ns, current_euid()));
> >> + print_symbol(KERN_EMERG "refcount error occurred at: %s\n",
> >> + instruction_pointer(regs));
> >> + preempt_disable();
> >> + show_regs(regs);
> >> + preempt_enable();
> >> +}
> >
> > Why is preemption disabled before calling show_regs()?
>
> I thought it was to avoid interleaving show_regs() output (I can't
> think of a way regs would be externally modified).
This code is running from interrupt context, so preemption shouldn't be
an issue unless I'm missing something.
--
Josh
next prev parent reply other threads:[~2017-05-01 22:45 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-25 22:56 [PATCH v2 0/2] x86, refcount: Implement fast refcount overflow Kees Cook
2017-04-25 22:56 ` [PATCH v2 1/2] x86, asm: Add suffix macro for GEN_*_RMWcc() Kees Cook
2017-04-25 22:56 ` [PATCH v2 2/2] x86, refcount: Implement fast refcount overflow protection Kees Cook
2017-04-26 0:25 ` Jann Horn
2017-04-26 3:52 ` Kees Cook
2017-04-27 1:31 ` kbuild test robot
2017-04-27 20:22 ` Kees Cook
2017-05-01 15:54 ` Josh Poimboeuf
2017-05-01 17:28 ` Kees Cook
2017-05-01 22:33 ` Josh Poimboeuf
2017-05-01 16:30 ` Josh Poimboeuf
2017-05-01 17:36 ` Kees Cook
2017-05-01 22:45 ` Josh Poimboeuf [this message]
2017-04-26 2:01 ` [PATCH v2 0/2] x86, refcount: Implement fast refcount overflow PaX Team
2017-04-26 3:59 ` Kees Cook
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