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    Subject[PATCH 4.9 129/310] PM / devfreq: Fix potential NULL pointer dereference in governor_store
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

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

    From: "Gustavo A. R. Silva" <garsilva@embeddedor.com>


    [ Upstream commit 63f1e05f7fe9ca509c60154d6a833abf96eecdc9 ]

    df->governor is being dereferenced before it is null checked,
    hence there is a potential null pointer dereference.

    Notice that df->governor is being null checked at line 1004:
    if (df->governor) {, which implies it might be null.

    Fix this by null checking df->governor before dereferencing it.

    Addresses-Coverity-ID: 1401988 ("Dereference before null check")
    Fixes: bcf23c79c4e4 ("PM / devfreq: Fix available_governor sysfs")
    Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
    Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
    Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
    Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/devfreq/devfreq.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    --- a/drivers/devfreq/devfreq.c
    +++ b/drivers/devfreq/devfreq.c
    @@ -943,7 +943,8 @@ static ssize_t governor_store(struct dev
    if (df->governor == governor) {
    ret = 0;
    goto out;
    - } else if (df->governor->immutable || governor->immutable) {
    + } else if ((df->governor && df->governor->immutable) ||
    + governor->immutable) {
    ret = -EINVAL;
    goto out;
    }

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