In the Linux kernel, the following vulnerability has been resolved: gpio: mvebu: fix NULL pointer dereference in suspend/resume mvebu_pwm_

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

gpio: mvebu: fix NULL pointer dereference in suspend/resume

mvebu_pwm_suspend() and mvebu_pwm_resume() are called for all GPIO
banks during suspend/resume, but not all banks have PWM functionality.
GPIO banks without PWM have mvchip->mvpwm set to NULL.

Calling mvebu_pwm_suspend() with mvpwm == NULL causes a NULL pointer
dereference when it tries to access mvpwm->blink_select.

Unable to handle kernel NULL pointer dereference at virtual address 00000020 when write
[00000020] *pgd=00000000
Internal error: Oops: 815 [#1] PREEMPT ARM
Modules linked in:
CPU: 0 UID: 0 PID: 406 Comm: sh Not tainted 6.12.74-rt12-yocto-standard-g4e96f98fb7db-dirty #353
Hardware name: Marvell Armada 370/XP (Device Tree)
PC is at regmap_mmio_read+0x38/0x54
LR is at regmap_mmio_read+0x38/0x54
pc : [<c05fd2ac>] lr : [<c05fd2ac>] psr: 200f0013
sp : f0c11d10 ip : 00000000 fp : c100d2f0
r10: c14fb854 r9 : 00000000 r8 : 00000000
r7 : c1799c00 r6 : 00000020 r5 : 00000020 r4 : c179c7c0
r3 : f0a231a0 r2 : 00000020 r1 : 00000020 r0 : 00000000
Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
Control: 10c5387d Table: 135ec059 DAC: 00000051
Call trace:
regmap_mmio_read from _regmap_bus_reg_read+0x78/0xac
_regmap_bus_reg_read from _regmap_read+0x60/0x154
_regmap_read from regmap_read+0x3c/0x60
regmap_read from mvebu_gpio_suspend+0xa4/0x14c
mvebu_gpio_suspend from dpm_run_callback+0x54/0x180
dpm_run_callback from device_suspend+0x124/0x630
device_suspend from dpm_suspend+0x124/0x270
dpm_suspend from dpm_suspend_start+0x64/0x6c
dpm_suspend_start from suspend_devices_and_enter+0x140/0x8e8
suspend_devices_and_enter from pm_suspend+0x2fc/0x308
pm_suspend from state_store+0x6c/0xc8
state_store from kernfs_fop_write_iter+0x10c/0x1f8
kernfs_fop_write_iter from vfs_write+0x270/0x468
vfs_write from ksys_write+0x70/0xf0
ksys_write from ret_fast_syscall+0x0/0x54

Add a NULL check for mvchip->mvpwm before calling the PWM
suspend/resume functions.