From: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
To: jeffxu@chromium.org
Cc: akpm@linux-foundation.org, keescook@chromium.org,
torvalds@linux-foundation.org, usama.anjum@collabora.com,
corbet@lwn.net, Liam.Howlett@oracle.com, jeffxu@google.com,
jorgelo@chromium.org, groeck@chromium.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-mm@kvack.org, jannh@google.com, sroettger@google.com,
pedro.falcato@gmail.com, linux-hardening@vger.kernel.org,
willy@infradead.org, gregkh@linuxfoundation.org,
deraadt@openbsd.org, surenb@google.com, merimus@google.com,
rdunlap@infradead.org
Subject: Re: [PATCH] munmap sealed memory cause memory to split (bug)
Date: Thu, 17 Oct 2024 10:48:35 +0100 [thread overview]
Message-ID: <7053a505-be80-48d0-8b5d-7ce52ba56c3a@lucifer.local> (raw)
In-Reply-To: <ac11e4c4-a1df-4d39-b7d1-ed9ebd65cd16@lucifer.local>
On Thu, Oct 17, 2024 at 10:46:10AM +0100, Lorenzo Stoakes wrote:
[snip]
> Anyway, let's try to decode (please take this as input as to how you should
> try to communicate these things):
>
>
> So we start with a VMA like this:
>
> 012345678901
> xxxxxxxxxxxx
>
> We then seal the middle, starting at offset 4:
>
> 012345678901
> xxxx****xxxx
>
> This sets the VM_SEALED flag in the middle and splits VMAs resulting in 3
> VMAs.
>
> We then attempt to unmap 4 pages from offset 2, but this fails, as
> expected.
>
> 012345678901
> xxxx****xxxx
> |--| fail
>
> We then attempt to unmap 4 pages from offset 6, but this fails, as
> expected.
>
> 012345678901
> xxxx****xxxx
> |--| fail
>
> At each stage we should observe 4 VMAs.
CORRECTION: 3 VMAs.
[snip]
next prev parent reply other threads:[~2024-10-17 9:49 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-17 2:26 jeffxu
2024-10-17 2:38 ` Jeff Xu
2024-10-17 6:03 ` Greg KH
2024-10-17 16:17 ` Jeff Xu
2024-10-17 8:18 ` Lorenzo Stoakes
2024-10-17 16:20 ` Jeff Xu
2024-10-17 19:14 ` Pedro Falcato
2024-10-17 19:16 ` Lorenzo Stoakes
2024-10-17 20:12 ` Jeff Xu
2024-10-17 9:46 ` Lorenzo Stoakes
2024-10-17 9:48 ` Lorenzo Stoakes [this message]
2024-10-17 9:59 ` Lorenzo Stoakes
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