This is a note to let you know that I've just added the patch titled
rpmsg: char: Fix race between the release of rpmsg_eptdev and cdev
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
rpmsg-char-fix-race-between-the-release-of-rpmsg_ept.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 29f6748164bc7c6086dcc02e11a0d577d1ea59ad
Author: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
Date: Mon Jan 10 10:47:37 2022 -0800
rpmsg: char: Fix race between the release of rpmsg_eptdev and cdev
[ Upstream commit 7a534ae89e34e9b51acb5a63dd0f88308178b46a ]
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: c0cdc19f84a4 ("rpmsg: Driver for user space endpoint interface")
Suggested-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
Signed-off-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
Reviewed-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220110104706.v6.2.Idde68b05b88d4a2e6e54766c653f3a6d9e419ce6@changeid
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index 0b69787a1cf7d..ac50ed7577651 100644
--- a/drivers/rpmsg/rpmsg_char.c
+++ b/drivers/rpmsg/rpmsg_char.c
@@ -92,7 +92,7 @@ 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:
