From: Dave Hansen <dave.hansen@intel.com>
To: Nadav Amit <nadav.amit@gmail.com>
Cc: Linux-MM <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Peter Xu <peterx@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will@kernel.org>, Yu Zhao <yuzhao@google.com>,
Nick Piggin <npiggin@gmail.com>,
"x86@kernel.org" <x86@kernel.org>
Subject: Re: [RESEND PATCH v3 2/5] x86/mm: check exec permissions on fault
Date: Fri, 11 Mar 2022 13:23:26 -0800 [thread overview]
Message-ID: <103853ef-3afb-bb94-5ffd-8318d1a1d1a0@intel.com> (raw)
In-Reply-To: <E46E0DA7-6427-4733-9D43-6CC1107194D6@gmail.com>
On 3/11/22 13:16, Nadav Amit wrote:
>> This is really about checking the sanity of the "hardware"-provided
>> error code. Let's just do it in handle_page_fault(), maybe hidden in a
>> function like:
>>
>> void check_error_code_sanity(unsigned long error_code)
>> {
>> WARN_ON_ONCE(...);
>> }
>>
>> You can leave the X86_PF_PK check in place for now. It's probably going
>> away soon anyway.
> Done. Thanks. But note that removing the check from access_error() means
> that if the assertion is broken, userspace might crash inadvertently
> (in contrast to the version I sent, which would have potentially led to
> infinite stream of page-faults). I don’t know which behavior is better,
> so let’s go with your version and just hope it doesn’t happen.
Actually, crashing sounds much nicer to me than infinite page faults.
It's a lot easier to debug, *especially* with a warning on dmesg.
prev parent reply other threads:[~2022-03-11 21:23 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-11 19:07 [RESEND PATCH v3 0/5] mm/mprotect: avoid unnecessary TLB flushes Nadav Amit
2022-03-11 19:07 ` [RESEND PATCH v3 1/5] x86: Detection of Knights Landing A/D leak Nadav Amit
2022-03-11 19:07 ` [RESEND PATCH v3 4/5] mm/mprotect: do not flush on permission promotion Nadav Amit
2022-03-11 22:45 ` Nadav Amit
2022-03-11 19:07 ` [RESEND PATCH v3 5/5] mm: avoid unnecessary flush on change_huge_pmd() Nadav Amit
2022-03-11 20:41 ` Dave Hansen
2022-03-11 20:53 ` Nadav Amit
[not found] ` <20220311190749.338281-3-namit@vmware.com>
2022-03-11 19:41 ` [RESEND PATCH v3 2/5] x86/mm: check exec permissions on fault Dave Hansen
2022-03-11 20:38 ` Nadav Amit
2022-03-11 20:59 ` Dave Hansen
2022-03-11 21:16 ` Nadav Amit
2022-03-11 21:23 ` Dave Hansen [this message]
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