CVE-2026-90334: tty: clear cdev pointer after cdev_add() failure
In the Linux kernel, the following vulnerability has been resolved:
tty: clear cdev pointer after cdevadd() failure
ttycdevadd() drops the cdev reference when cdevadd() fails, but leaves driver->cdevs[index] pointing to freed memory. ttyunregisterdevice() later passes that stale pointer to cdevdel(), causing a use-after-free.
Clear the slot after dropping the reference.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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Fixed in 6.6.157.1-1 - Upgrade
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debian/linuxto a version that resolves this vulnerability.Fixed in 6.1.190-1Fixed in 6.12.115-2Fixed in 7.2.12-1Fixed in 7.2.15-1 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 7.2.6 - Compensating control
In tty_cdev_add(), clear driver->cdevs[index] after cdev_add() fails and the cdev reference is dropped, so tty_unregister_device() cannot pass the stale pointer to cdev_del().
Event History
Frequently Asked Questions
Is a failed device-registration path required for this issue to occur?
Yes. The stale pointer is left only when cdev_add() fails and tty_cdev_add() drops the cdev reference without clearing driver->cdevs[index]. A later tty_unregister_device() call can then pass that freed pointer to cdev_del().
What change prevents the use-after-free?
Clear driver->cdevs[index] after dropping the cdev reference following a cdev_add() failure. This prevents tty_unregister_device() from using the stale pointer later.