Bug 2536246 (CVE-2026-90336)

Summary:	CVE-2026-90336 kernel: serial: core: clear freed pointers on uart_register_driver() failure
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's serial core component. When `uart_register_driver()` fails, pointers to freed memory are not properly cleared. This can allow a local attacker to cause a use-after-free condition by repeatedly attempting to register and bind a serial port. Successful exploitation of this vulnerability could lead to a system crash, resulting in a denial of service (DoS).	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-17 17:06:24 UTC

In the Linux kernel, the following vulnerability has been resolved:

serial: core: clear freed pointers on uart_register_driver() failure

uart_register_driver() leaves drv->state pointing to freed memory when
tty_alloc_driver() fails. If tty_register_driver() fails, drv->tty_driver
also retains a pointer after its reference is dropped.

Drivers that use drv->state as an "already registered" flag can then skip
registration on the next probe and pass the freed state to
uart_add_one_port().

This issue was found with failslab on QEMU's raspi1ap board by
failing registration and binding the PL011 port again.

Clear both pointers on their failure paths, as uart_unregister_driver()
already does.

Comment 1 gkamathe 2026-09-21 20:13:05 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90336.mbox