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    Subject[PATCH 5.19 049/192] perf: RISC-V: fix access beyond allocated array
    Date
    From: Sergey Matyukevich <sergey.matyukevich@syntacore.com>

    commit 20e0fbab16003ae23a9e86a64bcb93e3121587ca upstream.

    SBI firmware should report total number of firmware and hardware counters
    including unused ones or special ones. In this case the kernel doesn't need
    to make any assumptions about gaps in reported counters, e.g. excluded timer
    counter. That was fixed in OpenSBI v1.1 by commit 3f66465fb6bf ("lib: pmu:
    allow to use the highest available counter"). This kernel patch has no effect
    if SBI firmware behaves correctly. However it eliminates access beyond the
    allocated pmu_ctr_list if the kernel is used with OpenSBI older than v1.1.

    Fixes: e9991434596f ("RISC-V: Add perf platform driver based on SBI PMU extension")
    Signed-off-by: Sergey Matyukevich <sergey.matyukevich@syntacore.com>
    Reviewed-by: Atish Patra <atishp@rivosinc.com>
    Cc: stable@vger.kernel.org
    Link: https://lore.kernel.org/r/20220830155306.301714-2-geomatsi@gmail.com
    Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/perf/riscv_pmu_sbi.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/drivers/perf/riscv_pmu_sbi.c
    +++ b/drivers/perf/riscv_pmu_sbi.c
    @@ -467,7 +467,7 @@ static int pmu_sbi_get_ctrinfo(int nctr)
    if (!pmu_ctr_list)
    return -ENOMEM;

    - for (i = 0; i <= nctr; i++) {
    + for (i = 0; i < nctr; i++) {
    ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_GET_INFO, i, 0, 0, 0, 0, 0);
    if (ret.error)
    /* The logical counter ids are not expected to be contiguous */

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