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uio: Fix stale info pointer in failed registration path

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After device_add(), the UIO device is visible to userspace and /dev/uioX
can be opened. If a later setup step fails, __uio_register_device()
unwinds the device but leaves idev->info pointing at the caller-owned
struct uio_info.

That is unsafe when an opener races with the failed registration path.
The open file keeps a reference to the uio_device, while the caller sees
registration failure and may free its struct uio_info. Later file
operations can then follow idev->info and dereference freed memory.

Handle post-device_add() failures like unregister: remove UIO attributes
while the info pointer is still valid, then clear idev->info under
info_lock and wake existing waiters/async users before removing the
device and minor. This makes already-open file descriptors observe the
same "device gone" state as normal uio_unregister_device().

Fixes: a93e7b3315 ("uio: Prevent device destruction while fds are open")
Signed-off-by: Yuho Choi <dbgh9129@gmail.com>
Link: https://patch.msgid.link/20260630192714.1867170-1-dbgh9129@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Yuho Choi
2026-06-30 15:27:14 -04:00
committed by Greg Kroah-Hartman
parent 7bf924f96d
commit 67b6fc084b
1 changed files with 5 additions and 0 deletions
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5
drivers/uio/uio.c
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@@ -1057,6 +1057,11 @@ int __uio_register_device(struct module *owner,
err_request_irq:
uio_dev_del_attributes(idev);
err_uio_dev_add_attributes:
mutex_lock(&idev->info_lock);
idev->info = NULL;
mutex_unlock(&idev->info_lock);
wake_up_interruptible(&idev->wait);
kill_fasync(&idev->async_queue, SIGIO, POLL_HUP);
device_del(&idev->dev);
err_device_create:
uio_free_minor(idev->minor);