Linux kernel mailbox imx MU race on channel shutdown
CVE-2026-98903 Published on October 23, 2026
mailbox: imx: Add a channel shutdown field
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.
Products Associated with CVE-2026-98903
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Affected Versions
Linux:- Version 0a67003b1985c79811160af1b01aca07cd5fbc53 and below 02273054b2e94e53065ea5644265bb9d8f7ee2a7 is affected.
- Version 0a67003b1985c79811160af1b01aca07cd5fbc53 and below 944d8509c2220a2313d4a094a646507929fb6f8d is affected.
- Version 0a67003b1985c79811160af1b01aca07cd5fbc53 and below 5ccea7eacb7786c358833634f45700365f6c1d99 is affected.
- Version 5.7 is affected.
- Before 5.7 is unaffected.
- Version 6.12.111, <= 6.12.* is unaffected.
- Version 6.18.53, <= 6.18.* is unaffected.
- Version 7.2, <= * is unaffected.