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rpmsg: char: Fix race between the release of rpmsg_eptdev and cdev 

commit 7a534ae89e 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>
This commit is contained in:
Matthias Kaehlcke 2022-01-10 10:47:37 -08:00 committed by Greg Kroah-Hartman
parent 74d85e9fbc
commit d249b89621
1 changed files with 2 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
drivers/rpmsg/rpmsg_char.c
View File

@ -100,7 +100,7 @@ static int rpmsg_eptdev_destroy(struct device *dev, void *data)
/* wake up any blocked readers */
wake_up_interruptible(&eptdev->readq);
device_del(&eptdev->dev);
cdev_device_del(&eptdev->cdev, &eptdev->dev);
put_device(&eptdev->dev);
return 0;
@ -336,7 +336,6 @@ static void rpmsg_eptdev_release_device(struct device *dev)
ida_simple_remove(&rpmsg_ept_ida, dev->id);
ida_simple_remove(&rpmsg_minor_ida, MINOR(eptdev->dev.devt));
cdev_del(&eptdev->cdev);
kfree(eptdev);
}
@ -381,19 +380,13 @@ static int rpmsg_eptdev_create(struct rpmsg_ctrldev *ctrldev,
dev->id = ret;
dev_set_name(dev, "rpmsg%d", ret);
ret = cdev_add(&eptdev->cdev, dev->devt, 1);
ret = cdev_device_add(&eptdev->cdev, &eptdev->dev);
if (ret)
goto free_ept_ida;
/* We can now rely on the release function for cleanup */
dev->release = rpmsg_eptdev_release_device;
ret = device_add(dev);
if (ret) {
dev_err(dev, "device_add failed: %d\n", ret);
put_device(dev);
}
return ret;
free_ept_ida: