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    Subject[PATCH v2 1/2] extcon: fix hang and extcon_get/set_cable_state().
    Date
    Users of find_cable_index_by_name() will cause a kernel hang
    as the while loop counter is never incremented and end condition
    is never reached.

    extcon_get_cable_state() and extcon_set_cable_state() are broken
    because they use cable index instead of cable id. This causes
    the first cable state (cable.0) to be always invalid in sysfs
    or extcon_get_cable_state() users.

    Introduce a new function find_cable_id_by_name() that fixes
    both of the above issues.

    Fixes: commit 73b6ecdb93e8 ("extcon: Redefine the unique id of supported external connectors without 'enum extcon' type")
    Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Roger Quadros <rogerq@ti.com>
    ---
    drivers/extcon/extcon.c | 38 +++++++++++++++++++++++++++++---------
    1 file changed, 29 insertions(+), 9 deletions(-)

    diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c
    index 76157ab..987dd3c 100644
    --- a/drivers/extcon/extcon.c
    +++ b/drivers/extcon/extcon.c
    @@ -124,22 +124,34 @@ static int find_cable_index_by_id(struct extcon_dev *edev, const unsigned int id
    return -EINVAL;
    }

    -static int find_cable_index_by_name(struct extcon_dev *edev, const char *name)
    +static int find_cable_id_by_name(struct extcon_dev *edev, const char *name)
    {
    - unsigned int id = EXTCON_NONE;
    + unsigned int id = -EINVAL;
    int i = 0;

    - if (edev->max_supported == 0)
    - return -EINVAL;
    -
    - /* Find the the number of extcon cable */
    + /* Find the id of extcon cable */
    while (extcon_name[i]) {
    if (!strncmp(extcon_name[i], name, CABLE_NAME_MAX)) {
    id = i;
    break;
    }
    +
    + i++;
    }

    + return id;
    +};
    +
    +static int find_cable_index_by_name(struct extcon_dev *edev, const char *name)
    +{
    + unsigned int id = EXTCON_NONE;
    +
    + if (edev->max_supported == 0)
    + return -EINVAL;
    +
    + /* Find the the number of extcon cable */
    + id = find_cable_id_by_name(edev, name);
    +
    if (id == EXTCON_NONE)
    return -EINVAL;

    @@ -228,9 +240,11 @@ static ssize_t cable_state_show(struct device *dev,
    struct extcon_cable *cable = container_of(attr, struct extcon_cable,
    attr_state);

    + int i = cable->cable_index;
    +
    return sprintf(buf, "%d\n",
    extcon_get_cable_state_(cable->edev,
    - cable->cable_index));
    + cable->edev->supported_cable[i]));
    }

    /**
    @@ -341,6 +355,9 @@ int extcon_get_cable_state_(struct extcon_dev *edev, const unsigned int id)
    {
    int index;

    + if (id == EXTCON_NONE)
    + return -EINVAL;
    +
    index = find_cable_index_by_id(edev, id);
    if (index < 0)
    return index;
    @@ -361,7 +378,7 @@ EXPORT_SYMBOL_GPL(extcon_get_cable_state_);
    */
    int extcon_get_cable_state(struct extcon_dev *edev, const char *cable_name)
    {
    - return extcon_get_cable_state_(edev, find_cable_index_by_name
    + return extcon_get_cable_state_(edev, find_cable_id_by_name
    (edev, cable_name));
    }
    EXPORT_SYMBOL_GPL(extcon_get_cable_state);
    @@ -380,6 +397,9 @@ int extcon_set_cable_state_(struct extcon_dev *edev, unsigned int id,
    u32 state;
    int index;

    + if (id == EXTCON_NONE)
    + return -EINVAL;
    +
    index = find_cable_index_by_id(edev, id);
    if (index < 0)
    return index;
    @@ -404,7 +424,7 @@ EXPORT_SYMBOL_GPL(extcon_set_cable_state_);
    int extcon_set_cable_state(struct extcon_dev *edev,
    const char *cable_name, bool cable_state)
    {
    - return extcon_set_cable_state_(edev, find_cable_index_by_name
    + return extcon_set_cable_state_(edev, find_cable_id_by_name
    (edev, cable_name), cable_state);
    }
    EXPORT_SYMBOL_GPL(extcon_set_cable_state);
    --
    2.1.4


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