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    Subject[PATCH] perf: fix raw sample size if no sampling data is attached
    On 19.04.10 14:19:57, Stephane Eranian wrote:
    > > +       perf_sample_data_init(&data, 0);
    > > +       if (event->attr.sample_type & PERF_SAMPLE_RAW) {
    > > +               for (i = 1; i < size; i++)
    > > +                       rdmsrl(msr++, *buf++);
    > > +               raw.size = sizeof(u64) * size;
    > > +               raw.data = buffer;
    > > +               data.raw = &raw;
    > > +       }
    > > +
    >
    > Need to add the padding: raw.size = sizeof(u64) * size + sizeof(u32);
    >
    > > +       regs = *iregs; /* later: update ip from ibs sample */
    > > +
    > > +       if (perf_event_overflow(event, 1, &data, &regs))

    During code review I found a bug in perf_output_sample(). A fix is
    below.

    > > +               x86_pmu_stop(event);
    > > +       else
    > > +               __x86_pmu_enable_event(&event->hw, reenable);
    > > +
    > > +       return 1;
    > > +}

    --

    From 6373951f1c660400650066b73c3bb2f6d232be67 Mon Sep 17 00:00:00 2001
    From: Robert Richter <robert.richter@amd.com>
    Date: Fri, 7 May 2010 15:49:56 +0200
    Subject: [PATCH] perf: fix raw sample size if no sampling data is attached

    The header size of a raw sample is not included in the total size of a
    raw data sample. Thus, if no data is attached the size must be
    null. In this case a buffer overflow may occur when copying the
    sampling data.

    Signed-off-by: Robert Richter <robert.richter@amd.com>
    ---
    kernel/perf_event.c | 2 +-
    1 files changed, 1 insertions(+), 1 deletions(-)

    diff --git a/kernel/perf_event.c b/kernel/perf_event.c
    index 9dbe8cd..f6ddae9 100644
    --- a/kernel/perf_event.c
    +++ b/kernel/perf_event.c
    @@ -3229,7 +3229,7 @@ void perf_output_sample(struct perf_output_handle *handle,
    u32 size;
    u32 data;
    } raw = {
    - .size = sizeof(u32),
    + .size = 0,
    .data = 0,
    };
    perf_output_put(handle, raw);
    --
    1.7.0.3
    --
    Advanced Micro Devices, Inc.
    Operating System Research Center
    email: robert.richter@amd.com

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