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>

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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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drivers/uio/uio.c

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