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    Subject[PATCH v3 11/11] rpmsg: Fix kfree() of static memory on setting driver_override
    Date
    The driver_override field from platform driver should not be initialized
    from static memory (string literal) because the core later kfree() it,
    for example when driver_override is set via sysfs.

    Use dedicated helper to set driver_override properly.

    Fixes: 950a7388f02b ("rpmsg: Turn name service into a stand alone driver")
    Fixes: c0cdc19f84a4 ("rpmsg: Driver for user space endpoint interface")
    Cc: <stable@vger.kernel.org>
    Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
    ---
    drivers/rpmsg/rpmsg_core.c | 3 ++-
    drivers/rpmsg/rpmsg_internal.h | 13 +++++++++++--
    drivers/rpmsg/rpmsg_ns.c | 14 ++++++++++++--
    include/linux/rpmsg.h | 6 ++++--
    4 files changed, 29 insertions(+), 7 deletions(-)

    diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
    index d9e612f4f0f2..6e2bf2742973 100644
    --- a/drivers/rpmsg/rpmsg_core.c
    +++ b/drivers/rpmsg/rpmsg_core.c
    @@ -397,7 +397,8 @@ field##_store(struct device *dev, struct device_attribute *attr, \
    const char *buf, size_t sz) \
    { \
    struct rpmsg_device *rpdev = to_rpmsg_device(dev); \
    - char *new, *old; \
    + const char *old; \
    + char *new; \
    \
    new = kstrndup(buf, sz, GFP_KERNEL); \
    if (!new) \
    diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h
    index b1245d3ed7c6..31345d6e9a7e 100644
    --- a/drivers/rpmsg/rpmsg_internal.h
    +++ b/drivers/rpmsg/rpmsg_internal.h
    @@ -92,10 +92,19 @@ int rpmsg_release_channel(struct rpmsg_device *rpdev,
    */
    static inline int rpmsg_chrdev_register_device(struct rpmsg_device *rpdev)
    {
    + int ret;
    +
    strcpy(rpdev->id.name, "rpmsg_chrdev");
    - rpdev->driver_override = "rpmsg_chrdev";
    + ret = driver_set_override(&rpdev->dev, &rpdev->driver_override,
    + "rpmsg_chrdev", strlen("rpmsg_chrdev"));
    + if (ret)
    + return ret;
    +
    + ret = rpmsg_register_device(rpdev);
    + if (ret)
    + kfree(rpdev->driver_override);

    - return rpmsg_register_device(rpdev);
    + return ret;
    }

    #endif
    diff --git a/drivers/rpmsg/rpmsg_ns.c b/drivers/rpmsg/rpmsg_ns.c
    index 762ff1ae279f..95a51543f5ad 100644
    --- a/drivers/rpmsg/rpmsg_ns.c
    +++ b/drivers/rpmsg/rpmsg_ns.c
    @@ -20,12 +20,22 @@
    */
    int rpmsg_ns_register_device(struct rpmsg_device *rpdev)
    {
    + int ret;
    +
    strcpy(rpdev->id.name, "rpmsg_ns");
    - rpdev->driver_override = "rpmsg_ns";
    + ret = driver_set_override(&rpdev->dev, &rpdev->driver_override,
    + "rpmsg_ns", strlen("rpmsg_ns"));
    + if (ret)
    + return ret;
    +
    rpdev->src = RPMSG_NS_ADDR;
    rpdev->dst = RPMSG_NS_ADDR;

    - return rpmsg_register_device(rpdev);
    + ret = rpmsg_register_device(rpdev);
    + if (ret)
    + kfree(rpdev->driver_override);
    +
    + return ret;
    }
    EXPORT_SYMBOL(rpmsg_ns_register_device);

    diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
    index 02fa9116cd60..20c8cd1cde21 100644
    --- a/include/linux/rpmsg.h
    +++ b/include/linux/rpmsg.h
    @@ -41,7 +41,9 @@ struct rpmsg_channel_info {
    * rpmsg_device - device that belong to the rpmsg bus
    * @dev: the device struct
    * @id: device id (used to match between rpmsg drivers and devices)
    - * @driver_override: driver name to force a match
    + * @driver_override: driver name to force a match; do not set directly,
    + * because core frees it; use driver_set_override() to
    + * set or clear it.
    * @src: local address
    * @dst: destination address
    * @ept: the rpmsg endpoint of this channel
    @@ -51,7 +53,7 @@ struct rpmsg_channel_info {
    struct rpmsg_device {
    struct device dev;
    struct rpmsg_device_id id;
    - char *driver_override;
    + const char *driver_override;
    u32 src;
    u32 dst;
    struct rpmsg_endpoint *ept;
    --
    2.32.0
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