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From: Johannes Berg <johannes@sipsolutions.net>
To: David Gow <davidgow@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>,
	Patricia Alfonso <trishalfonso@google.com>,
	Jeff Dike <jdike@addtoit.com>,
	Richard Weinberger <richard@nod.at>,
	Anton Ivanov <anton.ivanov@cambridgegreys.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Brendan Higgins <brendanhiggins@google.com>,
	linux-um <linux-um@lists.infradead.org>,
	LKML <linux-kernel@vger.kernel.org>,
	kasan-dev <kasan-dev@googlegroups.com>
Subject: Re: [PATCH] UML: add support for KASAN under x86_64
Date: Tue, 31 Mar 2020 09:43:59 +0200	[thread overview]
Message-ID: <19cf82d3c3d76ad62a47beee162fa9ff768a3a01.camel@sipsolutions.net> (raw)
In-Reply-To: <CABVgOSnz2heYvXytvhwA3RO_3dX=8vKrC+b8a6GLZV8eD3Fcow@mail.gmail.com> (sfid-20200331_081511_061239_730E62F6)

On Mon, 2020-03-30 at 23:14 -0700, David Gow wrote:
> 
> I spent a little time playing around with this, and was able to get
> mac80211 

mac80211, or mac80211-hwsim? I can load a few modules, but then it
crashes on say the third (usually, but who knows what this depends on).

> loading if I force-enabled CONFIG_KASAN_VMALLOC (alongside
> bumping up the shadow memory address).

Not sure I tried that combination though.

> The test-bpf module was still failing, though — which may or may not
> have been related to how bpf uses vmalloc().

I think I got some trouble also with just stack unwinding and other
random things faulting in the vmalloc and/or shadow space ...

> I do like the idea of trying to push the shadow memory allocation
> through UML's PTE code, but confess to not understanding it
> particularly well. 

Me neither. I just noticed that all the vmalloc and kasan-vmalloc do all
the PTE handling, so things might easily clash if you have
CONFIG_KASAN_VMALLOC, which we do want eventually.

> I imagine it'd require pushing the KASAN
> initialisation back until after init_physmem, and having the shadow
> memory be backed by the physmem file? Unless there's a clever way of
> allocating the shadow memory early, and then hooking it into the page
> tables/etc when those are initialised (akin to how on x86 there's a
> separate early shadow memory stage while things are still being set
> up, maybe?)

Pretty sure we should be able to hook it up later, but I haven't really
dug deeply yet.

johannes


WARNING: multiple messages have this Message-ID (diff)
From: Johannes Berg <johannes@sipsolutions.net>
To: David Gow <davidgow@google.com>
Cc: Patricia Alfonso <trishalfonso@google.com>,
	Richard Weinberger <richard@nod.at>,
	Jeff Dike <jdike@addtoit.com>,
	Brendan Higgins <brendanhiggins@google.com>,
	LKML <linux-kernel@vger.kernel.org>,
	kasan-dev <kasan-dev@googlegroups.com>,
	linux-um <linux-um@lists.infradead.org>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Anton Ivanov <anton.ivanov@cambridgegreys.com>
Subject: Re: [PATCH] UML: add support for KASAN under x86_64
Date: Tue, 31 Mar 2020 09:43:59 +0200	[thread overview]
Message-ID: <19cf82d3c3d76ad62a47beee162fa9ff768a3a01.camel@sipsolutions.net> (raw)
In-Reply-To: <CABVgOSnz2heYvXytvhwA3RO_3dX=8vKrC+b8a6GLZV8eD3Fcow@mail.gmail.com> (sfid-20200331_081511_061239_730E62F6)

On Mon, 2020-03-30 at 23:14 -0700, David Gow wrote:
> 
> I spent a little time playing around with this, and was able to get
> mac80211 

mac80211, or mac80211-hwsim? I can load a few modules, but then it
crashes on say the third (usually, but who knows what this depends on).

> loading if I force-enabled CONFIG_KASAN_VMALLOC (alongside
> bumping up the shadow memory address).

Not sure I tried that combination though.

> The test-bpf module was still failing, though — which may or may not
> have been related to how bpf uses vmalloc().

I think I got some trouble also with just stack unwinding and other
random things faulting in the vmalloc and/or shadow space ...

> I do like the idea of trying to push the shadow memory allocation
> through UML's PTE code, but confess to not understanding it
> particularly well. 

Me neither. I just noticed that all the vmalloc and kasan-vmalloc do all
the PTE handling, so things might easily clash if you have
CONFIG_KASAN_VMALLOC, which we do want eventually.

> I imagine it'd require pushing the KASAN
> initialisation back until after init_physmem, and having the shadow
> memory be backed by the physmem file? Unless there's a clever way of
> allocating the shadow memory early, and then hooking it into the page
> tables/etc when those are initialised (akin to how on x86 there's a
> separate early shadow memory stage while things are still being set
> up, maybe?)

Pretty sure we should be able to hook it up later, but I haven't really
dug deeply yet.

johannes


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  reply	other threads:[~2020-03-31  7:44 UTC|newest]

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-26  0:46 [PATCH] UML: add support for KASAN under x86_64 Patricia Alfonso
2020-02-26  0:46 ` Patricia Alfonso
2020-02-26  1:19 ` Brendan Higgins
2020-02-26  1:19   ` Brendan Higgins
2020-02-26 15:24 ` Dmitry Vyukov
2020-02-26 15:24   ` Dmitry Vyukov
2020-03-06  0:03 ` Patricia Alfonso
2020-03-06  0:03   ` Patricia Alfonso
2020-03-11 10:32   ` Johannes Berg
2020-03-11 10:32     ` Johannes Berg
2020-03-11 10:46     ` Dmitry Vyukov
2020-03-11 10:46       ` Dmitry Vyukov
2020-03-11 11:18     ` Johannes Berg
2020-03-11 11:18       ` Johannes Berg
2020-03-11 11:40       ` Johannes Berg
2020-03-11 11:40         ` Johannes Berg
2020-03-11 17:34       ` Dmitry Vyukov
2020-03-11 17:34         ` Dmitry Vyukov
2020-03-20 13:39         ` Johannes Berg
2020-03-20 13:39           ` Johannes Berg
2020-03-20 15:18           ` Dmitry Vyukov
2020-03-20 15:18             ` Dmitry Vyukov
2020-03-30  7:43             ` Johannes Berg
2020-03-30  7:43               ` Johannes Berg
2020-03-30  8:38               ` Dmitry Vyukov
2020-03-30  8:38                 ` Dmitry Vyukov
2020-03-30  8:41                 ` Johannes Berg
2020-03-30  8:41                   ` Johannes Berg
2020-03-31  6:14                   ` David Gow
2020-03-31  6:14                     ` David Gow
2020-03-31  7:43                     ` Johannes Berg [this message]
2020-03-31  7:43                       ` Johannes Berg
2020-03-31 16:39                   ` Patricia Alfonso
2020-03-31 16:39                     ` Patricia Alfonso
2020-03-31 16:54                     ` Richard Weinberger
2020-03-11 22:32     ` Patricia Alfonso
2020-03-11 22:32       ` Patricia Alfonso
2020-03-11 22:44       ` Johannes Berg
2020-03-11 22:44         ` Johannes Berg
2022-05-24 10:34         ` Vincent Whitchurch
2022-05-24 10:34           ` Vincent Whitchurch
2022-05-24 10:45           ` Johannes Berg
2022-05-24 10:45             ` Johannes Berg
2022-05-24 19:35           ` David Gow
2022-05-24 19:35             ` David Gow
2022-05-25 11:17             ` Vincent Whitchurch
2022-05-25 11:17               ` Vincent Whitchurch
2022-05-26  1:01               ` [RFC PATCH v3] " David Gow
2022-05-26  1:01                 ` David Gow
2022-05-26  9:29                 ` Johannes Berg
2022-05-26  9:29                   ` Johannes Berg
2022-05-27  5:31                 ` Dmitry Vyukov
2022-05-27  5:31                   ` Dmitry Vyukov
2022-05-27  7:32                   ` Johannes Berg
2022-05-27  7:32                     ` Johannes Berg
2022-05-27 10:36                 ` Johannes Berg
2022-05-27 10:36                   ` Johannes Berg
2022-05-27 13:05                 ` Johannes Berg
2022-05-27 13:05                   ` Johannes Berg
2022-05-27 13:09                   ` Dmitry Vyukov
2022-05-27 13:09                     ` Dmitry Vyukov
2022-05-27 13:15                     ` Johannes Berg
2022-05-27 13:15                       ` Johannes Berg
2022-05-27 13:18                       ` Dmitry Vyukov
2022-05-27 13:18                         ` Dmitry Vyukov
2022-05-27 13:27                         ` Johannes Berg
2022-05-27 13:27                           ` Johannes Berg
2022-05-27 13:52                           ` Dmitry Vyukov
2022-05-27 13:52                             ` Dmitry Vyukov
2022-05-27 14:27                             ` Johannes Berg
2022-05-27 14:27                               ` Johannes Berg
2022-05-27 15:46                               ` Dmitry Vyukov
2022-05-27 15:46                                 ` Dmitry Vyukov
2020-03-29 19:06     ` [PATCH] " Richard Weinberger
2020-03-29 19:06       ` Richard Weinberger

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