Re: [PATCH] gpio: mvebu: fix NULL pointer dereference in suspend/resume

[Baruch Siach]

Hi Yun Zhou,

On Mon, Jun 08 2026, Yun Zhou wrote:
> 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.
>
> Fixes: 85b7d8abfec7 ("gpio: mvebu: add pwm support for Armada 370/XP/38x")

Commit summary for 85b7d8abfec7 is "gpio: mvebu: add pwm support for
Armada 8K/7K". I could not find a commit matching the summary line above
in upstream git. Commit 757642f9a584e ("gpio: mvebu: Add limited PWM
support") introduced mvebu_pwm_suspend() and mvebu_pwm_resume(). I think
that is the one being fixed.

baruch

> Signed-off-by: Yun Zhou <yun.zhou@xxxxxxxxxxxxx>
> ---
>  drivers/gpio/gpio-mvebu.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
> index 22c36b79e249..c030d1f00abc 100644
> --- a/drivers/gpio/gpio-mvebu.c
> +++ b/drivers/gpio/gpio-mvebu.c
> @@ -996,7 +996,7 @@ static int mvebu_gpio_suspend(struct platform_device *pdev, pm_message_t state)
>  		BUG();
>  	}
>  
> -	if (IS_REACHABLE(CONFIG_PWM))
> +	if (IS_REACHABLE(CONFIG_PWM) && mvchip->mvpwm)
>  		mvebu_pwm_suspend(mvchip);
>  
>  	return 0;
> @@ -1048,7 +1048,7 @@ static int mvebu_gpio_resume(struct platform_device *pdev)
>  		BUG();
>  	}
>  
> -	if (IS_REACHABLE(CONFIG_PWM))
> +	if (IS_REACHABLE(CONFIG_PWM) && mvchip->mvpwm)
>  		mvebu_pwm_resume(mvchip);
>  
>  	return 0;

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