On 11/19/2025 6:56 PM, Dawei Li wrote:
On Wed, Nov 19, 2025 at 12:07:02PM +0800, Zhongqiu Han wrote:
On 11/18/2025 11:41 PM, Dawei Li wrote:
put_device() is called on error path of rpmsg_eptdev_add() to cleanup
resource attached to eptdev->dev, unfortunately it's bogus cause
dev->release() is not set yet.
When a struct device instance is destroyed, driver core framework checks
the possible release() callback from candidates below:
- struct device::release()
- dev->type->release()
- dev->class->dev_release()
Rpmsg eptdev owns none of them so WARN() will complain the absence of
release().
Fix it by:
- Pre-assign dev->release() before potential error path.
- Check before ida_free() in dev->release().
By fixing error path of rpmsg_eptdev_add() and fixing potential memory
leak in rpmsg_anonymous_eptdev_create(), this work paves the way of rework
of rpmsg_eptdev_add() and its callers.
Fixes: c0cdc19f84a4 ("rpmsg: Driver for user space endpoint interface")
Signed-off-by: Dawei Li <[email protected]>
---
drivers/rpmsg/rpmsg_char.c | 26 +++++++++++++-------------
1 file changed, 13 insertions(+), 13 deletions(-)
diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index 34b35ea74aab..373b627581e8 100644
--- a/drivers/rpmsg/rpmsg_char.c
+++ b/drivers/rpmsg/rpmsg_char.c
@@ -408,8 +408,13 @@ static void rpmsg_eptdev_release_device(struct device *dev)
{
struct rpmsg_eptdev *eptdev = dev_to_eptdev(dev);
- ida_free(&rpmsg_ept_ida, dev->id);
- if (eptdev->dev.devt)
+ /*
+ * release() can be invoked from error path of rpmsg_eptdev_add(),
+ * WARN() will be fired if ida_free() is feed with invalid ID.
+ */
+ if (likely(ida_exists(&rpmsg_ept_ida, dev->id)))
+ ida_free(&rpmsg_ept_ida, dev->id);
+ if (eptdev->dev.devt && likely(ida_exists(&rpmsg_minor_ida,
MINOR(eptdev->dev.devt))))
ida_free(&rpmsg_minor_ida, MINOR(eptdev->dev.devt));
kfree(eptdev);
}
@@ -458,6 +463,8 @@ static int rpmsg_eptdev_add(struct rpmsg_eptdev *eptdev,
struct device *dev = &eptdev->dev;
int ret;
+ dev->release = rpmsg_eptdev_release_device;
+
eptdev->chinfo = chinfo;
if (cdev) {
@@ -471,7 +478,7 @@ static int rpmsg_eptdev_add(struct rpmsg_eptdev *eptdev,
/* Anonymous inode device still need device name for dev_err() and
friends */
ret = ida_alloc(&rpmsg_ept_ida, GFP_KERNEL);
if (ret < 0)
- goto free_minor_ida;
+ goto free_eptdev;
dev->id = ret;
dev_set_name(dev, "rpmsg%d", ret);
@@ -480,22 +487,13 @@ static int rpmsg_eptdev_add(struct rpmsg_eptdev *eptdev,
if (cdev) {
ret = cdev_device_add(&eptdev->cdev, &eptdev->dev);
if (ret)
- goto free_ept_ida;
+ goto free_eptdev;
}
- /* We can now rely on the release function for cleanup */
- dev->release = rpmsg_eptdev_release_device;
-
return ret;
-free_ept_ida:
- ida_free(&rpmsg_ept_ida, dev->id);
-free_minor_ida:
- if (cdev)
- ida_free(&rpmsg_minor_ida, MINOR(dev->devt));
free_eptdev:
put_device(dev);
- kfree(eptdev);
Hi Dawei,
Thanks for your new version~
Patch 1/3 will introduce a use-after-free of eptdev in func
rpmsg_anonymous_eptdev_create(),
https://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux.git/tree/drivers/rpmsg/rpmsg_char.c?h=for-next#n548
even though this issue will be resolved in 2/3. However, 1/3, as an
independent commit, should not introduce a new bug.
FWIW, it's not new bug introduced by this commit, it's introduced by
2410558f5f11, which is supposed to be fixed in patch[2/3].
Hi Dawei,
I checked commit 2410558f5f11 and see that the issue existed before this
patch. Thanks for clarifying,
And new reorganize of series is trying to address the comments from
Mathieu[1], If I understand it correctly.
Bjorn, Mathieu,
What's your inputs on this? I will respin v5 if you find it necessary.
Diff between v5 from v4:
patch[1/3]: Remove dev_err(&eptdev->dev) from rpmsg_anonymous_eptdev_create();
patch[2/3]: Bring back dev_err(&eptdev->dev) to rpmsg_anonymous_eptdev_create();
[1] https://lore.kernel.org/all/aRd8mDzQWXtEFnmt@p14s/
return ret;
}
@@ -561,6 +559,8 @@ int rpmsg_anonymous_eptdev_create(struct rpmsg_device
*rpdev, struct device *par
if (!ret)
*pfd = fd;
+ else
+ put_device(&eptdev->dev);
return ret;
}
--
Thx and BRs,
Zhongqiu Han
Thanks,
Dawei
--
Thx and BRs,
Zhongqiu Han
