rpmsg: char: Fix race between the release of rpmsg_eptdev and cdev
commit7a534ae89e
upstream. struct rpmsg_eptdev contains a struct cdev. The current code frees the rpmsg_eptdev struct in rpmsg_eptdev_destroy(), but the cdev is a managed object, therefore its release is not predictable and the rpmsg_eptdev could be freed before the cdev is entirely released. The cdev_device_add/del() API was created to address this issue (see commit '233ed09d7fda ("chardev: add helper function to register char devs with a struct device")'), use it instead of cdev add/del(). Fixes:c0cdc19f84
("rpmsg: Driver for user space endpoint interface") Suggested-by: Bjorn Andersson <bjorn.andersson@linaro.org> Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> Reviewed-by: Stephen Boyd <swboyd@chromium.org> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> Link: https://lore.kernel.org/r/20220110104706.v6.2.Idde68b05b88d4a2e6e54766c653f3a6d9e419ce6@changeid Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -92,7 +92,7 @@ static int rpmsg_eptdev_destroy(struct device *dev, void *data)
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/* wake up any blocked readers */
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wake_up_interruptible(&eptdev->readq);
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device_del(&eptdev->dev);
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cdev_device_del(&eptdev->cdev, &eptdev->dev);
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put_device(&eptdev->dev);
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return 0;
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@ -335,7 +335,6 @@ static void rpmsg_eptdev_release_device(struct device *dev)
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ida_simple_remove(&rpmsg_ept_ida, dev->id);
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ida_simple_remove(&rpmsg_minor_ida, MINOR(eptdev->dev.devt));
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cdev_del(&eptdev->cdev);
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kfree(eptdev);
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}
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@ -380,19 +379,13 @@ static int rpmsg_eptdev_create(struct rpmsg_ctrldev *ctrldev,
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dev->id = ret;
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dev_set_name(dev, "rpmsg%d", ret);
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ret = cdev_add(&eptdev->cdev, dev->devt, 1);
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ret = cdev_device_add(&eptdev->cdev, &eptdev->dev);
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if (ret)
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goto free_ept_ida;
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/* We can now rely on the release function for cleanup */
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dev->release = rpmsg_eptdev_release_device;
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ret = device_add(dev);
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if (ret) {
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dev_err(dev, "device_add failed: %d\n", ret);
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put_device(dev);
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}
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return ret;
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free_ept_ida:
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