From: Jann Horn <jann@thejh.net> To: Daniel Axtens <dja@axtens.net> Cc: kernel-hardening@lists.openwall.com, linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>, HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>, Vitaly Kuznetsov <vkuznets@redhat.com>, Baoquan He <bhe@redhat.com>, Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Subject: Re: [RFC] kernel/panic: place an upper limit on number of oopses Date: Wed, 13 Jan 2016 00:51:17 +0100 [thread overview] Message-ID: <20160112235117.GA2537@pc.thejh.net> (raw) In-Reply-To: <87mvsa5q40.fsf@gamma.ozlabs.ibm.com> [-- Attachment #1: Type: text/plain, Size: 852 bytes --] On Wed, Jan 13, 2016 at 10:34:39AM +1100, Daniel Axtens wrote: > Jann Horn <jann@thejh.net> writes: > > + * limit is reached, just panic. > > + * The constant used as limit should be low enough to > > + * mitigate this kind of exploitation attempt, but high > > + * enough to avoid unnecessary panics. > > + */ > > + if (atomic_inc_return(&oops_counter) >= 0x100000 && > > + panic_on_oops == 0) { > Do you need to check panic_on_oops? If it was 1 you'd already have > paniced, right? [...] > > + pr_emerg("oopsed too often, setting panic_on_oops=1\n"); > > + panic_on_oops = 1; > Would it be easier to just panic here, rather than wait for another oops? Ah, yes. So the code would be just this, apart from the definition of oops_counter: if (atomic_inc_return(&oops_counter) >= 0x100000) panic("oopsed too often\n"); [-- Attachment #2: Digital signature --] [-- Type: application/pgp-signature, Size: 819 bytes --]
WARNING: multiple messages have this Message-ID (diff)
From: Jann Horn <jann@thejh.net> To: Daniel Axtens <dja@axtens.net> Cc: kernel-hardening@lists.openwall.com, linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>, HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>, Vitaly Kuznetsov <vkuznets@redhat.com>, Baoquan He <bhe@redhat.com>, Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Subject: [kernel-hardening] Re: [RFC] kernel/panic: place an upper limit on number of oopses Date: Wed, 13 Jan 2016 00:51:17 +0100 [thread overview] Message-ID: <20160112235117.GA2537@pc.thejh.net> (raw) In-Reply-To: <87mvsa5q40.fsf@gamma.ozlabs.ibm.com> [-- Attachment #1: Type: text/plain, Size: 852 bytes --] On Wed, Jan 13, 2016 at 10:34:39AM +1100, Daniel Axtens wrote: > Jann Horn <jann@thejh.net> writes: > > + * limit is reached, just panic. > > + * The constant used as limit should be low enough to > > + * mitigate this kind of exploitation attempt, but high > > + * enough to avoid unnecessary panics. > > + */ > > + if (atomic_inc_return(&oops_counter) >= 0x100000 && > > + panic_on_oops == 0) { > Do you need to check panic_on_oops? If it was 1 you'd already have > paniced, right? [...] > > + pr_emerg("oopsed too often, setting panic_on_oops=1\n"); > > + panic_on_oops = 1; > Would it be easier to just panic here, rather than wait for another oops? Ah, yes. So the code would be just this, apart from the definition of oops_counter: if (atomic_inc_return(&oops_counter) >= 0x100000) panic("oopsed too often\n"); [-- Attachment #2: Digital signature --] [-- Type: application/pgp-signature, Size: 819 bytes --]
next prev parent reply other threads:[~2016-01-12 23:51 UTC|newest] Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-01-12 19:25 [RFC] kernel/panic: place an upper limit on number of oopses Jann Horn 2016-01-12 19:25 ` [kernel-hardening] " Jann Horn 2016-01-12 23:34 ` Daniel Axtens 2016-01-12 23:34 ` [kernel-hardening] " Daniel Axtens 2016-01-12 23:51 ` Jann Horn [this message] 2016-01-12 23:51 ` Jann Horn 2016-01-13 0:20 ` Solar Designer 2016-01-13 0:20 ` [kernel-hardening] " Solar Designer 2016-01-13 0:33 ` Daniel Axtens 2016-01-13 0:33 ` [kernel-hardening] " Daniel Axtens 2016-01-13 18:08 ` Jann Horn 2016-01-13 18:08 ` [kernel-hardening] " Jann Horn 2016-01-17 3:58 ` Jann Horn
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