CVE-2026-98903

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

mailbox: imx: Add a channel shutdown field

sashiko complained about possible teardown problem. The scenario

CPU 0 CPU 1 imx mu isr() imx mu shutdown() imx mu xcr rmw(priv, IMX MU RCR, 0, IMX MU xCR RIEn(priv->dcfg->type, cp->idx)); imx mu specific rx() imx mu xcr rmw(priv, IMX MU RCR, IMX MU xCR RIEn(priv->dcfg->type, 0), 0); free irq()

The RX event remains enabled because in this short window the RX event was disabled in ->shutdown() while the interrupt was active and then enabled again by the ISR while ->shutdown waited in free irq().

This race requires timing and if happens can be problematic on shared handlers if the "removed" channel triggers an interrupt. In this case the irq-core will shutdown the interrupt with the "nobody cared" message.

Introduce imx mu con priv::shutdown to signal that the channel is shutting down. This flag is set with the lock held (by imx mu xcr clr shut()). The unmask side uses imx mu xcr set act() which only enables the event if the channel has not been shutdown and serialises on the same lock.