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From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Kevin Sheldrake <Kevin.Sheldrake@microsoft.com>
Cc: "bpf@vger.kernel.org" <bpf@vger.kernel.org>,
	KP Singh <kpsingh@google.com>
Subject: Re: [PATCH bpf-next v2] Update perf ring buffer to prevent corruption
Date: Thu, 5 Nov 2020 11:07:25 -0800	[thread overview]
Message-ID: <CAEf4Bza0unqU9QWBtuh_y07OGnC_HxOK_RwO+UTJ_0XhQdm1Vg@mail.gmail.com> (raw)
In-Reply-To: <VI1PR8303MB00802FE5D289E0D7BA95B7DDFBEE0@VI1PR8303MB0080.EURPRD83.prod.outlook.com>

On Thu, Nov 5, 2020 at 7:16 AM Kevin Sheldrake
<Kevin.Sheldrake@microsoft.com> wrote:
>
> Resent due to some failure at my end.  Apologies if it arrives twice.
>
> From 63e34d4106b4dd767f9bfce951f8a35f14b52072 Mon Sep 17 00:00:00 2001
> From: Kevin Sheldrake <kevin.sheldrake@microsoft.com>
> Date: Thu, 5 Nov 2020 12:18:53 +0000
> Subject: [PATCH] Update perf ring buffer to prevent corruption from
>  bpf_perf_output_event()
>
> The bpf_perf_output_event() helper takes a sample size parameter of u64, but
> the underlying perf ring buffer uses a u16 internally. This 64KB maximum size
> has to also accommodate a variable sized header. Failure to observe this
> restriction can result in corruption of the perf ring buffer as samples
> overlap.
>
> Track the sample size and return -E2BIG if too big to fit into the u16
> size parameter.
>
> Signed-off-by: Kevin Sheldrake <kevin.sheldrake@microsoft.com>
> ---

LGTM.

Acked-by: Andrii Nakryiko <andrii@kernel.org>

>  include/linux/perf_event.h |  2 +-
>  kernel/events/core.c       | 40 ++++++++++++++++++++++++++--------------
>  2 files changed, 27 insertions(+), 15 deletions(-)
>

[...]

  reply	other threads:[~2020-11-05 19:07 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-05 15:16 [PATCH bpf-next v2] Update perf ring buffer to prevent corruption Kevin Sheldrake
2020-11-05 19:07 ` Andrii Nakryiko [this message]
2020-11-05 19:37   ` KP Singh
2020-11-06  4:19 ` Alexei Starovoitov
2020-11-09 11:29   ` Peter Zijlstra
2020-11-09 14:22     ` [EXTERNAL] " Kevin Sheldrake
2020-11-09 17:55       ` Peter Zijlstra
2020-11-09 18:22   ` Peter Zijlstra

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