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    Subject[PATCH 5.0 40/43] perf/x86/intel: Fix memory corruption
    Date
    5.0-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Peter Zijlstra <peterz@infradead.org>

    commit ede271b059463731cbd6dffe55ffd70d7dbe8392 upstream.

    Through:

    validate_event()
    x86_pmu.get_event_constraints(.idx=-1)
    tfa_get_event_constraints()
    dyn_constraint()

    cpuc->constraint_list[-1] is used, which is an obvious out-of-bound access.

    In this case, simply skip the TFA constraint code, there is no event
    constraint with just PMC3, therefore the code will never result in the
    empty set.

    Fixes: 400816f60c54 ("perf/x86/intel: Implement support for TSX Force Abort")
    Reported-by: Tony Jones <tonyj@suse.com>
    Reported-by: "DSouza, Nelson" <nelson.dsouza@intel.com>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Tested-by: Tony Jones <tonyj@suse.com>
    Tested-by: "DSouza, Nelson" <nelson.dsouza@intel.com>
    Cc: eranian@google.com
    Cc: jolsa@redhat.com
    Cc: stable@kernel.org
    Link: https://lkml.kernel.org/r/20190314130705.441549378@infradead.org
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/x86/events/intel/core.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/arch/x86/events/intel/core.c
    +++ b/arch/x86/events/intel/core.c
    @@ -3398,7 +3398,7 @@ tfa_get_event_constraints(struct cpu_hw_
    /*
    * Without TFA we must not use PMC3.
    */
    - if (!allow_tsx_force_abort && test_bit(3, c->idxmsk)) {
    + if (!allow_tsx_force_abort && test_bit(3, c->idxmsk) && idx >= 0) {
    c = dyn_constraint(cpuc, c, idx);
    c->idxmsk64 &= ~(1ULL << 3);
    c->weight--;

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