From: Christopher Lameter <cl@linux.com>
To: Anton Eidelman <anton@lightbitslabs.com>
Cc: Kees Cook <keescook@chromium.org>,
Matthew Wilcox <willy@infradead.org>,
Laura Abbott <labbott@redhat.com>, Linux-MM <linux-mm@kvack.org>,
linux-hardened@lists.openwall.com
Subject: Re: HARDENED_USERCOPY will BUG on multiple slub objects coalesced into an sk_buff fragment
Date: Tue, 5 Jun 2018 21:43:32 +0000 [thread overview]
Message-ID: <01000163d1e7b1bf-7bd8565a-7d5e-4d61-b998-6e59557cf8e4-000000@email.amazonses.com> (raw)
In-Reply-To: <CAKYffwqf5EhabhFwT85iTYNLjpR0noQ9Kua+2aOYNZ5AaJAWOw@mail.gmail.com>
On Tue, 5 Jun 2018, Anton Eidelman wrote:
> What I am still wondering about (and investigating), is how kernel_sendpage()
> with slab payload results in slab payload on another socket RX.
> Do you see how page ref-counting can be broken with extra references taken
> on a slab page containing the fragments, and dropped when networking is
> done with them?
The slab allocators do not use page refcounting. The objects may be
destroyed via poisioning etc if you use kfree() while still holding a
refcount on the page. Even without poisoning the slab allocator may
overwrite the object.
next prev parent reply other threads:[~2018-06-05 21:43 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-01 0:03 Anton Eidelman
2018-06-01 19:02 ` Laura Abbott
2018-06-01 20:49 ` Kees Cook
2018-06-01 20:58 ` Matthew Wilcox
2018-06-01 21:55 ` Kees Cook
2018-06-01 23:34 ` Anton Eidelman
2018-06-05 15:27 ` Christopher Lameter
2018-06-05 20:45 ` Anton Eidelman
2018-06-05 21:43 ` Christopher Lameter [this message]
2018-06-05 14:51 ` Christopher Lameter
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