Re: [PATCH v2] staging: media: max96712: fix kernel oops when removing module

["Niklas Söderlund" <niklas.soderlund@ragnatech.se>]

Hello Laurentiu,

On 2024-12-17 08:51:50 +0200, Laurentiu Palcu wrote:
> The following kernel oops is thrown when trying to remove the max96712
> module:
> 
> Unable to handle kernel paging request at virtual address 00007375746174db
> Mem abort info:
>   ESR = 0x0000000096000004
>   EC = 0x25: DABT (current EL), IL = 32 bits
>   SET = 0, FnV = 0
>   EA = 0, S1PTW = 0
>   FSC = 0x04: level 0 translation fault
> Data abort info:
>   ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
>   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
>   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
> user pgtable: 4k pages, 48-bit VAs, pgdp=000000010af89000
> [00007375746174db] pgd=0000000000000000, p4d=0000000000000000
> Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
> Modules linked in: crct10dif_ce polyval_ce mxc_jpeg_encdec flexcan
>     snd_soc_fsl_sai snd_soc_fsl_asoc_card snd_soc_fsl_micfil dwc_mipi_csi2
>     imx_csi_formatter polyval_generic v4l2_jpeg imx_pcm_dma can_dev
>     snd_soc_imx_audmux snd_soc_wm8962 snd_soc_imx_card snd_soc_fsl_utils
>     max96712(C-) rpmsg_ctrl rpmsg_char pwm_fan fuse
>     [last unloaded: imx8_isi]
> CPU: 0 UID: 0 PID: 754 Comm: rmmod
> 	    Tainted: G         C    6.12.0-rc6-06364-g327fec852c31 #17
> Tainted: [C]=CRAP
> Hardware name: NXP i.MX95 19X19 board (DT)
> pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : led_put+0x1c/0x40
> lr : v4l2_subdev_put_privacy_led+0x48/0x58
> sp : ffff80008699bbb0
> x29: ffff80008699bbb0 x28: ffff00008ac233c0 x27: 0000000000000000
> x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000
> x23: ffff000080cf1170 x22: ffff00008b53bd00 x21: ffff8000822ad1c8
> x20: ffff000080ff5c00 x19: ffff00008b53be40 x18: 0000000000000000
> x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
> x14: 0000000000000004 x13: ffff0000800f8010 x12: 0000000000000000
> x11: ffff000082acf5c0 x10: ffff000082acf478 x9 : ffff0000800f8010
> x8 : 0101010101010101 x7 : 7f7f7f7f7f7f7f7f x6 : fefefeff6364626d
> x5 : 8080808000000000 x4 : 0000000000000020 x3 : 00000000553a3dc1
> x2 : ffff00008ac233c0 x1 : ffff00008ac233c0 x0 : ff00737574617473
> Call trace:
>  led_put+0x1c/0x40
>  v4l2_subdev_put_privacy_led+0x48/0x58
>  v4l2_async_unregister_subdev+0x2c/0x1a4
>  max96712_remove+0x1c/0x38 [max96712]
>  i2c_device_remove+0x2c/0x9c
>  device_remove+0x4c/0x80
>  device_release_driver_internal+0x1cc/0x228
>  driver_detach+0x4c/0x98
>  bus_remove_driver+0x6c/0xbc
>  driver_unregister+0x30/0x60
>  i2c_del_driver+0x54/0x64
>  max96712_i2c_driver_exit+0x18/0x1d0 [max96712]
>  __arm64_sys_delete_module+0x1a4/0x290
>  invoke_syscall+0x48/0x10c
>  el0_svc_common.constprop.0+0xc0/0xe0
>  do_el0_svc+0x1c/0x28
>  el0_svc+0x34/0xd8
>  el0t_64_sync_handler+0x120/0x12c
>  el0t_64_sync+0x190/0x194
> Code: f9000bf3 aa0003f3 f9402800 f9402000 (f9403400)
> ---[ end trace 0000000000000000 ]---
> 
> This happens because in v4l2_i2c_subdev_init(), the i2c_set_cliendata()
> is called again and the data is overwritten to point to sd, instead of
> priv. So, in remove(), the wrong pointer is passed to
> v4l2_async_unregister_subdev(), leading to a crash.
> 
> Fixes: 5814f32fef13 ("media: staging: max96712: Add basic support for MAX96712 GMSL2 deserializer")
> Signed-off-by: Laurentiu Palcu <laurentiu.palcu@oss.nxp.com>

Thanks for catching this.

Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

> ---
> Changes in v2:
>  * removed call to i2c_set_clientdata() in probe;
>  * cleaned up the trace in commit message as the tmux status line string
>    sneaked into it;
> 
> Thanks,
> Laurentiu
> 
>  drivers/staging/media/max96712/max96712.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/media/max96712/max96712.c b/drivers/staging/media/max96712/max96712.c
> index ede02e8c891cb..0751b2e048958 100644
> --- a/drivers/staging/media/max96712/max96712.c
> +++ b/drivers/staging/media/max96712/max96712.c
> @@ -418,7 +418,6 @@ static int max96712_probe(struct i2c_client *client)
>  	priv->info = of_device_get_match_data(&client->dev);
>  
>  	priv->client = client;
> -	i2c_set_clientdata(client, priv);
>  
>  	priv->regmap = devm_regmap_init_i2c(client, &max96712_i2c_regmap);
>  	if (IS_ERR(priv->regmap))
> @@ -448,7 +447,8 @@ static int max96712_probe(struct i2c_client *client)
>  
>  static void max96712_remove(struct i2c_client *client)
>  {
> -	struct max96712_priv *priv = i2c_get_clientdata(client);
> +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> +	struct max96712_priv *priv = container_of(sd, struct max96712_priv, sd);
>  
>  	v4l2_async_unregister_subdev(&priv->sd);
>  
> -- 
> 2.44.1
> 

-- 
Kind Regards,
Niklas Söderlund