CVE-2023-54287: 
Linux Kernel vulnerability analysis and mitigation

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

tty: serial: imx: disable Ageing Timer interrupt request irq

There maybe pending USR interrupt before requesting irq, however uart_add_one_port has not executed, so there will be kernel panic: [ 0.795668] Unable to handle kernel NULL pointer dereference at virtual addre ss 0000000000000080 [ 0.802701] Mem abort info: [ 0.805367] ESR = 0x0000000096000004 [ 0.808950] EC = 0x25: DABT (current EL), IL = 32 bits [ 0.814033] SET = 0, FnV = 0 [ 0.816950] EA = 0, S1PTW = 0 [ 0.819950] FSC = 0x04: level 0 translation fault [ 0.824617] Data abort info: [ 0.827367] ISV = 0, ISS = 0x00000004 [ 0.831033] CM = 0, WnR = 0 [ 0.833866] [0000000000000080] user address but active_mm is swapper [ 0.839951] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP [ 0.845953] Modules linked in: [ 0.848869] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.1.1+g56321e101aca #1 [ 0.855617] Hardware name: Freescale i.MX8MP EVK (DT) [ 0.860452] pstate: 000000c5 (nzcv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 0.867117] pc : __imx_uart_rxint.constprop.0+0x11c/0x2c0 [ 0.872283] lr : imx_uart_int+0xf8/0x1ec

The issue only happends in the inmate linux when Jailhouse hypervisor enabled. The test procedure is: while true; do jailhouse enable imx8mp.cell jailhouse cell linux xxxx sleep 10 jailhouse cell destroy 1 jailhouse disable sleep 5 done

And during the upper test, press keys to the 2nd linux console. When jailhouse cell destroy 1, the 2nd linux has no chance to put the uart to a quiese state, so USR1/2 may has pending interrupts. Then when jailhosue cell linux xx to start 2nd linux again, the issue trigger.

In order to disable irqs before requesting them, both UCR1 and UCR2 irqs should be disabled, so here fix that, disable the Ageing Timer interrupt in UCR2 as UCR1 does.