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    Subject[PATCH 4.19 447/639] perf/ioctl: Add check for the sample_period value
    Date
    From: Ravi Bangoria <ravi.bangoria@linux.ibm.com>

    [ Upstream commit 913a90bc5a3a06b1f04c337320e9aeee2328dd77 ]

    perf_event_open() limits the sample_period to 63 bits. See:

    0819b2e30ccb ("perf: Limit perf_event_attr::sample_period to 63 bits")

    Make ioctl() consistent with it.

    Also on PowerPC, negative sample_period could cause a recursive
    PMIs leading to a hang (reported when running perf-fuzzer).

    Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
    Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Stephane Eranian <eranian@google.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Vince Weaver <vincent.weaver@maine.edu>
    Cc: acme@kernel.org
    Cc: linuxppc-dev@lists.ozlabs.org
    Cc: maddy@linux.vnet.ibm.com
    Cc: mpe@ellerman.id.au
    Fixes: 0819b2e30ccb ("perf: Limit perf_event_attr::sample_period to 63 bits")
    Link: https://lkml.kernel.org/r/20190604042953.914-1-ravi.bangoria@linux.ibm.com
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    kernel/events/core.c | 3 +++
    1 file changed, 3 insertions(+)

    diff --git a/kernel/events/core.c b/kernel/events/core.c
    index 751888cbed5c0..16af86ab24c42 100644
    --- a/kernel/events/core.c
    +++ b/kernel/events/core.c
    @@ -5012,6 +5012,9 @@ static int perf_event_period(struct perf_event *event, u64 __user *arg)
    if (perf_event_check_period(event, value))
    return -EINVAL;

    + if (!event->attr.freq && (value & (1ULL << 63)))
    + return -EINVAL;
    +
    event_function_call(event, __perf_event_period, &value);

    return 0;
    --
    2.20.1


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