CVE-2022-49841

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

serial: imx: Add missing .thaw_noirq hook

The following warning is seen with non-console UART instance when system hibernates.

[ 37.371969] ------------[ cut here ]------------ [ 37.376599] uart3rootclk already disabled [ 37.380810] WARNING: CPU: 0 PID: 296 at drivers/clk/clk.c:952 clkcoredisable+0xa4/0xb0 ... [ 37.506986] Call trace: [ 37.509432] clkcoredisable+0xa4/0xb0 [ 37.513270] clkdisable+0x34/0x50 [ 37.516672] imxuartthaw+0x38/0x5c [ 37.520250] platformpmthaw+0x30/0x6c [ 37.524089] dpmruncallback.constprop.0+0x3c/0xd4 [ 37.528972] deviceresume+0x7c/0x160 [ 37.532633] dpmresume+0xe8/0x230 [ 37.536036] hibernationsnapshot+0x288/0x430 [ 37.540397] hibernate+0x10c/0x2e0 [ 37.543798] statestore+0xc4/0xd0 [ 37.547203] kobjattrstore+0x1c/0x30 [ 37.550953] sysfskfwrite+0x48/0x60 [ 37.554619] kernfsfopwriteiter+0x118/0x1ac [ 37.559063] newsyncwrite+0xe8/0x184 [ 37.562812] vfswrite+0x230/0x290 [ 37.566214] ksyswrite+0x68/0xf4 [ 37.569529] _arm64syswrite+0x20/0x2c [ 37.573452] invokesyscall.constprop.0+0x50/0xf0 [ 37.578156] doel0svc+0x11c/0x150 [ 37.581648] el0svc+0x30/0x140 [ 37.584792] el0t64synchandler+0xe8/0xf0 [ 37.588976] el0t64sync+0x1a0/0x1a4 [ 37.592639] ---[ end trace 56e22eec54676d75 ]---

On hibernating, pm core calls into related hooks in sequence like:

.freeze
.freeze_noirq
.thaw_noirq
.thaw

With .thaw_noirq hook being absent, the clock will be disabled in a unbalanced call which results the warning above.

imx_uart_freeze()
    clk_prepare_enable()
imx_uart_suspend_noirq()
    clk_disable()
imx_uart_thaw
    clk_disable_unprepare()

Adding the missing .thawnoirq hook as imxuartresumenoirq() will have the call sequence corrected as below and thus fix the warning.

imx_uart_freeze()
    clk_prepare_enable()
imx_uart_suspend_noirq()
    clk_disable()
imx_uart_resume_noirq()
    clk_enable()
imx_uart_thaw
    clk_disable_unprepare()