From: Karl Mehltretter <kmehltretter@gmail.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jirislaby@kernel.org>
Cc: Karl Mehltretter <kmehltretter@gmail.com>,
linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v3 4/5] tty: clear cdev pointer after cdev_add() failure
Date: Fri, 31 Jul 2026 20:04:57 +0200 [thread overview]
Message-ID: <20260731180457.10964-1-kmehltretter@gmail.com> (raw)
tty_cdev_add() drops the cdev reference when cdev_add() fails, but
leaves driver->cdevs[index] pointing to freed memory.
tty_unregister_device() later passes that stale pointer to cdev_del(),
causing a use-after-free.
Clear the slot after dropping the reference.
Fixes: c1a752ba2d6b ("tty: don't leak cdev in tty_cdev_add()")
Assisted-by: Claude:claude-fable-5
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
---
drivers/tty/tty_io.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index e742bf9d8631..4889076b975f 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -3167,8 +3167,10 @@ static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
driver->cdevs[index]->ops = &tty_fops;
driver->cdevs[index]->owner = driver->owner;
err = cdev_add(driver->cdevs[index], dev, count);
- if (err)
+ if (err) {
kobject_put(&driver->cdevs[index]->kobj);
+ driver->cdevs[index] = NULL;
+ }
return err;
}
--
2.53.0
reply other threads:[~2026-07-31 18:05 UTC|newest]
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