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    Subject[PATCH 06/13] coresight: Fix csdev connections initialisation
    Date
    From: Suzuki K Poulose <suzuki.poulose@arm.com>

    This is a cleanup patch.

    coresight_device->conns holds an array to point to the devices
    connected to the OUT ports of a component. Sinks, e.g ETR, do not
    have an OUT port (nr_outport = 0), as it streams the trace to
    memory via AXI.

    At coresight_register() we do :

    conns = kcalloc(csdev->nr_outport, sizeof(*conns), GFP_KERNEL);
    if (!conns) {
    ret = -ENOMEM;
    goto err_kzalloc_conns;
    }

    For ETR, since the total size requested for kcalloc is zero, the return
    value is, ZERO_SIZE_PTR ( != NULL). Hence, csdev->conns = ZERO_SIZE_PTR
    which cannot be verified later to contain a valid pointer. The code which
    accesses the csdev->conns is bounded by the csdev->nr_outport check,
    hence we don't try to dereference the ZERO_SIZE_PTR. This patch cleans
    up the csdev->conns initialisation to make sure we initialise it
    properly(i.e, either NULL or valid conns array).

    Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
    Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
    Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
    ---
    drivers/hwtracing/coresight/coresight.c | 24 ++++++++++++++----------
    1 file changed, 14 insertions(+), 10 deletions(-)

    diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
    index ceeaaea41ed6..bb20ee9747e1 100644
    --- a/drivers/hwtracing/coresight/coresight.c
    +++ b/drivers/hwtracing/coresight/coresight.c
    @@ -894,7 +894,7 @@ struct coresight_device *coresight_register(struct coresight_desc *desc)
    int nr_refcnts = 1;
    atomic_t *refcnts = NULL;
    struct coresight_device *csdev;
    - struct coresight_connection *conns;
    + struct coresight_connection *conns = NULL;

    csdev = kzalloc(sizeof(*csdev), GFP_KERNEL);
    if (!csdev) {
    @@ -922,16 +922,20 @@ struct coresight_device *coresight_register(struct coresight_desc *desc)

    csdev->nr_inport = desc->pdata->nr_inport;
    csdev->nr_outport = desc->pdata->nr_outport;
    - conns = kcalloc(csdev->nr_outport, sizeof(*conns), GFP_KERNEL);
    - if (!conns) {
    - ret = -ENOMEM;
    - goto err_kzalloc_conns;
    - }

    - for (i = 0; i < csdev->nr_outport; i++) {
    - conns[i].outport = desc->pdata->outports[i];
    - conns[i].child_name = desc->pdata->child_names[i];
    - conns[i].child_port = desc->pdata->child_ports[i];
    + /* Initialise connections if there is at least one outport */
    + if (csdev->nr_outport) {
    + conns = kcalloc(csdev->nr_outport, sizeof(*conns), GFP_KERNEL);
    + if (!conns) {
    + ret = -ENOMEM;
    + goto err_kzalloc_conns;
    + }
    +
    + for (i = 0; i < csdev->nr_outport; i++) {
    + conns[i].outport = desc->pdata->outports[i];
    + conns[i].child_name = desc->pdata->child_names[i];
    + conns[i].child_port = desc->pdata->child_ports[i];
    + }
    }

    csdev->conns = conns;
    --
    2.7.4
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