From: Lorenz Bauer <lmb@cloudflare.com>
To: Bui Quang Minh <minhquangbui99@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
"David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
hawk@kernel.org, John Fastabend <john.fastabend@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>, Martin Lau <kafai@fb.com>,
Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
kpsingh@kernel.org, Jakub Sitnicki <jakub@cloudflare.com>,
Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] bpf: Fix integer overflow in argument calculation for bpf_map_area_alloc
Date: Tue, 26 Jan 2021 09:36:57 +0000 [thread overview]
Message-ID: <CACAyw99bEYWJCSGqfLiJ9Jp5YE1ZsZSiJxb4RFUTwbofipf0dA@mail.gmail.com> (raw)
In-Reply-To: <20210126082606.3183-1-minhquangbui99@gmail.com>
On Tue, 26 Jan 2021 at 08:26, Bui Quang Minh <minhquangbui99@gmail.com> wrote:
>
> In 32-bit architecture, the result of sizeof() is a 32-bit integer so
> the expression becomes the multiplication between 2 32-bit integer which
> can potentially leads to integer overflow. As a result,
> bpf_map_area_alloc() allocates less memory than needed.
>
> Fix this by casting 1 operand to u64.
Some quick thoughts:
* Should this have a Fixes tag?
* Seems like there are quite a few similar calls scattered around
(cpumap, etc.). Did you audit these as well?
* I'd prefer a calloc style version of bpf_map_area_alloc although
that might conflict with Fixes tag.
Lorenz
--
Lorenz Bauer | Systems Engineer
6th Floor, County Hall/The Riverside Building, SE1 7PB, UK
www.cloudflare.com
next prev parent reply other threads:[~2021-01-26 14:52 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-26 8:26 [PATCH] bpf: Fix integer overflow in argument calculation for bpf_map_area_alloc Bui Quang Minh
2021-01-26 9:36 ` Lorenz Bauer [this message]
2021-01-27 4:23 ` Bui Quang Minh
2021-01-27 5:09 ` Bui Quang Minh
2021-01-28 0:41 ` Daniel Borkmann
2021-05-17 15:10 ` Bui Quang Minh
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