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    Subject[PATCH 2/2] applesmc: Perform some more sanity checking on temperatures
    Date
    It seems that the two-byte temperature format is intended to be signed
    ("sp78" appears to mean "signed, decimal point, 7 bits before, 8 bits
    after") and it doesn't seem terribly plausible that we'll get any of these
    machines below freezing. It's probably more reasonable to assume that
    negative values indicate errors and drop them.

    Signed-off-by: Matthew Garrett <mjg@redhat.com>
    ---
    drivers/hwmon/applesmc.c | 4 ++++
    1 files changed, 4 insertions(+), 0 deletions(-)

    diff --git a/drivers/hwmon/applesmc.c b/drivers/hwmon/applesmc.c
    index 6c98b60..c1eead4 100644
    --- a/drivers/hwmon/applesmc.c
    +++ b/drivers/hwmon/applesmc.c
    @@ -744,6 +744,10 @@ static ssize_t applesmc_show_temperature(struct device *dev,
    return ret;

    if (entry->len == 2) {
    + if (buffer[0] >= 0x80) {
    + /* The two byte format is signed - ignore negative */
    + return -EINVAL;
    + }
    temp = buffer[0] * 1000;
    temp += (buffer[1] >> 6) * 250;
    } else {
    --
    1.7.3.3


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