staging: media: max96712: fix kernel oops when removing module

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: 5814f32 ("media: staging: max96712: Add basic support for MAX96712 GMSL2 deserializer")
Signed-off-by: Laurentiu Palcu <[email protected]>
Cc: [email protected]
Reviewed-by: Niklas Söderlund <[email protected]>
Reviewed-by: Ricardo Ribalda <[email protected]>
Signed-off-by: Sakari Ailus <[email protected]>
Signed-off-by: Mauro Carvalho Chehab <[email protected]>

Author: Laurentiu Palcu

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);