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] uart3_root_clk already disabled [ 37.380810] WARNING: CPU: 0 PID: 296 at drivers/clk/clk.c:952 clk_core_disable+0xa4/0xb0 … [ 37.506986] Call trace: [ 37.509432] clk_core_disable+0xa4/0xb0 [ 37.513270] clk_disable+0x34/0x50 [ 37.516672] imx_uart_thaw+0x38/0x5c [ 37.520250] platform_pm_thaw+0x30/0x6c [ 37.524089] dpm_run_callback.constprop.0+0x3c/0xd4 [ 37.528972] device_resume+0x7c/0x160 [ 37.532633] dpm_resume+0xe8/0x230 [ 37.536036] hibernation_snapshot+0x288/0x430 [ 37.540397] hibernate+0x10c/0x2e0 [ 37.543798] state_store+0xc4/0xd0 [ 37.547203] kobj_attr_store+0x1c/0x30 [ 37.550953] sysfs_kf_write+0x48/0x60 [ 37.554619] kernfs_fop_write_iter+0x118/0x1ac [ 37.559063] new_sync_write+0xe8/0x184 [ 37.562812] vfs_write+0x230/0x290 [ 37.566214] ksys_write+0x68/0xf4 [ 37.569529] __arm64_sys_write+0x20/0x2c [ 37.573452] invoke_syscall.constprop.0+0x50/0xf0 [ 37.578156] do_el0_svc+0x11c/0x150 [ 37.581648] el0_svc+0x30/0x140 [ 37.584792] el0t_64_sync_handler+0xe8/0xf0 [ 37.588976] el0t_64_sync+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 .thaw_noirq hook as imx_uart_resume_noirq() 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()

Affected Software

References

• https://git.kernel.org/stable/c/0a3160f4ffc70ee4bfa1521f698dace06e6091fd
• https://git.kernel.org/stable/c/4561d8008a467cb05ac632a215391d6b787f40aa
• https://git.kernel.org/stable/c/476b09e07bd519ec7ba5941a6a6f9a02256dbb21
• https://git.kernel.org/stable/c/ae22294e213a402a70fa1731538367d1b758ffe7
• https://git.kernel.org/stable/c/e3f9d87d6f0732827c443bd1474df21c2fad704b
• https://git.kernel.org/stable/c/e401312ca6e180ee1bd65f6a766e99dd40aa95e7