From: Daniel Micay <danielmicay@gmail.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Jann Horn <jannh@google.com>,
linux-mm@kvack.org,
Kernel Hardening <kernel-hardening@lists.openwall.com>,
kernel list <linux-kernel@vger.kernel.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [RFC] Warn the user when they could overflow mapcount
Date: Thu, 8 Feb 2018 14:33:58 -0500 [thread overview]
Message-ID: <CA+DvKQLHcFc3+kW_SnD6hs53yyD5Zi+uAeSgDMm1tRzxqy-Opg@mail.gmail.com> (raw)
In-Reply-To: <20180208185648.GB9524@bombadil.infradead.org>
I don't think the kernel can get away with the current approach.
Object sizes and counts on 64-bit should be 64-bit unless there's a
verifiable reason they can get away with 32-bit. Having it use leak
memory isn't okay, just much less bad than vulnerabilities exploitable
beyond just denial of service.
Every 32-bit reference count should probably have a short comment
explaining why it can't overflow on 64-bit... if that can't be written
or it's too complicated to demonstrate, it probably needs to be
64-bit. It's one of many pervasive forms of integer overflows in the
kernel... :(
next prev parent reply other threads:[~2018-02-08 19:33 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-08 2:11 [RFC] Warn the user when they could overflow mapcount Matthew Wilcox
2018-02-08 2:56 ` Jann Horn
2018-02-08 4:04 ` Matthew Wilcox
2018-02-08 17:58 ` valdis.kletnieks
2018-02-08 18:05 ` Daniel Micay
2018-02-08 18:56 ` Matthew Wilcox
2018-02-08 19:33 ` Daniel Micay [this message]
2018-02-08 19:42 ` Matthew Wilcox
2018-02-08 19:48 ` Daniel Micay
2018-02-08 20:21 ` Matthew Wilcox
2018-02-08 21:37 ` [RFC] Limit mappings to ten per page per process Matthew Wilcox
2018-02-09 4:26 ` Kirill A. Shutemov
2018-02-14 13:51 ` Matthew Wilcox
2018-02-14 14:05 ` Kirill A. Shutemov
2018-02-09 1:47 ` [RFC] Warn the user when they could overflow mapcount Daniel Micay
2018-02-08 3:18 ` Tobin C. Harding
2018-02-08 4:06 ` Matthew Wilcox
2018-03-02 21:26 ` [RFC] Handle mapcount overflows Matthew Wilcox
2018-03-02 22:03 ` Matthew Wilcox
2019-05-01 14:41 ` Jann Horn
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