From: Dave Hansen <dave.hansen@intel.com>
To: Robert Kueffner <r.m.kueffner@gmail.com>,
Kyle Huey <me@kylehuey.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: Memory protection keys: Signal handlers crash if pkey0 is write-disabled
Date: Thu, 7 Sep 2023 14:31:13 -0700 [thread overview]
Message-ID: <c0159d08-e69d-0329-5ca9-68fd26cab0c8@intel.com> (raw)
In-Reply-To: <FF299375-B46F-46D0-90A9-333959FE9380@gmail.com>
On 9/7/23 14:22, Robert Kueffner wrote:
> Is there some way to make this work, or is it generally not possible
> to successfully handle exceptions if WD0=true?
It's theoretically possible, but it's in a grey area. The kernel can't
easily try to respect PKRU *and* override it for things like decoding
userspace instructions.
PKRU should get reset to a value that permits reads and writes to pkey-0
before the signal frame is created. But you're obviously tripping over
it anyway.
I assume that *something* is trying to access pkey-0-protected memory.
Any idea what that is? Which entity is doing that access and what are
they accessing? The page fault tracepoints might come in handy.
next prev parent reply other threads:[~2023-09-07 21:31 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-07 21:22 Robert Kueffner
2023-09-07 21:31 ` Dave Hansen [this message]
2023-09-07 23:07 ` Robert Kueffner
2023-09-08 15:14 ` Dave Hansen
2023-09-08 15:43 ` Robert Kueffner
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