[PATCH] ASoC: rockchip: i2s: Fix NULL pointer dereference when pinctrl is not found

[Alexandru Elisei]

Commit a5450aba737d ("ASoC: rockchip: i2s: switch BCLK to GPIO") switched
BCLK to GPIO functions when probing the i2s bus interface, but missed
adding a check for when devm_pinctrl_get() returns an error.  This can lead
to the following NULL pointer dereference on a rockpro64-v2 if there are no
"pinctrl" properties in the i2s device tree node:

[    0.658381] rockchip-i2s ff880000.i2s: failed to find i2s default state
[    0.658993] rockchip-i2s ff880000.i2s: failed to find i2s gpio state
[    0.660072] rockchip-i2s ff890000.i2s: failed to find i2s default state
[    0.660670] rockchip-i2s ff890000.i2s: failed to find i2s gpio state
[    0.661716] rockchip-i2s ff8a0000.i2s: failed to find i2s pinctrl
[    0.662276] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000005
[    0.663061] Mem abort info:
[    0.663317]   ESR = 0x0000000096000004
[    0.663658]   EC = 0x25: DABT (current EL), IL = 32 bits
[    0.664136]   SET = 0, FnV = 0
[    0.664171] mmc2: SDHCI controller on fe330000.mmc [fe330000.mmc] using ADMA
[    0.664409]   EA = 0, S1PTW = 0
[    0.664415]   FSC = 0x04: level 0 translation fault
[    0.664421] Data abort info:
[    0.666050]   ISV = 0, ISS = 0x00000004
[    0.666399]   CM = 0, WnR = 0
[    0.666671] [0000000000000005] user address but active_mm is swapper
[    0.667240] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[    0.667742] Modules linked in:
[    0.668028] CPU: 5 PID: 1 Comm: swapper/0 Not tainted 5.19.0-rc6 #300
[    0.668608] Hardware name: Pine64 RockPro64 v2.0 (DT)
[    0.669062] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[    0.669689] pc : pinctrl_lookup_state+0x20/0xc0
[    0.670110] lr : rockchip_i2s_probe+0x1a8/0x54c
[    0.670527] sp : ffff80000a17bb30
[    0.670829] x29: ffff80000a17bb30 x28: 0000000000000000 x27: ffff8000097c04c8
[    0.671480] x26: ffff800009871060 x25: ffff800009871078 x24: ffff000001c11368
[    0.672129] x23: ffff8000092dc850 x22: ffffffffffffffed x21: ffff8000096f7e98
[    0.672776] x20: ffffffffffffffed x19: ffff000001d92480 x18: ffffffffffffffff
[    0.673423] x17: 000000040044ffff x16: ffff0000f77db2d0 x15: 0764076e07690766
[    0.674070] x14: 0720076f07740720 x13: ffff800009e129f0 x12: 000000000000038d
[    0.674717] x11: 000000000000012f x10: ffff800009e6a9f0 x9 : ffff800009e129f0
[    0.675364] x8 : 00000000ffffefff x7 : ffff800009e6a9f0 x6 : 80000000fffff000
[    0.676011] x5 : 000000000000bff4 x4 : 0000000000000000 x3 : 0000000000000000
[    0.676657] x2 : 0000000000000000 x1 : ffff8000096f7e98 x0 : ffffffffffffffed
[    0.677304] Call trace:
[    0.677531]  pinctrl_lookup_state+0x20/0xc0
[    0.677914]  rockchip_i2s_probe+0x1a8/0x54c
[    0.678297]  platform_probe+0x68/0xc0
[    0.678638]  really_probe.part.0+0x9c/0x2ac
[    0.679027]  __driver_probe_device+0x98/0x144
[    0.679429]  driver_probe_device+0xac/0x140
[    0.679814]  __driver_attach+0xf8/0x184
[    0.680169]  bus_for_each_dev+0x70/0xd0
[    0.680524]  driver_attach+0x24/0x30
[    0.680856]  bus_add_driver+0x150/0x200
[    0.681210]  driver_register+0x78/0x130
[    0.681560]  __platform_driver_register+0x28/0x34
[    0.681988]  rockchip_i2s_driver_init+0x1c/0x28
[    0.682407]  do_one_initcall+0x50/0x1c0
[    0.682760]  kernel_init_freeable+0x204/0x288
[    0.683160]  kernel_init+0x28/0x13c
[    0.683482]  ret_from_fork+0x10/0x20
[    0.683816] Code: aa0003f4 a9025bf5 aa0003f6 aa0103f5 (f8418e93)
[    0.684365] ---[ end trace 0000000000000000 ]---
[    0.684813] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
[    0.685500] SMP: stopping secondary CPUs
[    0.685995] Kernel Offset: disabled
[    0.686310] CPU features: 0x800,00105811,00001086
[    0.686736] Memory Limit: none
[    0.687021] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]---

Check that i2s->pinctrl is valid before attempting to search for the
bclk_on and bclk_off pinctrl states.

Fixes: a5450aba737d ("ASoC: rockchip: i2s: switch BCLK to GPIO")
Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
---

Full log at [1], config at [2] (pastebins expire after 6 months).

I'm not familiar with this part of the kernel, I did my best to come up
with an explanation and a fix for the panic.

Read Documentation/devicetree/bindings/sound/rockchip-i2s.yaml, which has the
definition for the i2s nodes with the same compatible string as the i2s@ff8a0000
that is causing the panic (which is, "rockchip,rk3399-i2s"
"rockchip,rk3066-i2s"). There's no mention there of a "pinctrl" property, maybe
I'm reading the docs wrong, or maybe the board devicetree also needs fixing.

[1] https://pastebin.com/vuRVDsKk
[2] https://pastebin.com/3yDMF7YE

 sound/soc/rockchip/rockchip_i2s.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sound/soc/rockchip/rockchip_i2s.c b/sound/soc/rockchip/rockchip_i2s.c
index 99a128a666fb..c9fedf6eb2e6 100644
--- a/sound/soc/rockchip/rockchip_i2s.c
+++ b/sound/soc/rockchip/rockchip_i2s.c
@@ -808,8 +808,11 @@ static int rockchip_i2s_probe(struct platform_device *pdev)
 
 	i2s->bclk_ratio = 64;
 	i2s->pinctrl = devm_pinctrl_get(&pdev->dev);
-	if (IS_ERR(i2s->pinctrl))
+	if (IS_ERR(i2s->pinctrl)) {
 		dev_err(&pdev->dev, "failed to find i2s pinctrl\n");
+		ret = PTR_ERR(i2s->pinctrl);
+		goto err_clk;
+	}
 
 	i2s->bclk_on = pinctrl_lookup_state(i2s->pinctrl,
 				   "bclk_on");
-- 
2.37.0