2022-12-21 05:48:42

by Jishnu Prakash

Subject: [PATCH] spmi: Add a check for remove callback when removing a SPMI driver

When removing a SPMI driver, there can be a crash due to NULL pointer
dereference if it does not have a remove callback defined. This is
one such call trace observed when removing the QCOM SPMI PMIC driver:

dump_backtrace.cfi_jt+0x0/0x8
dump_stack_lvl+0xd8/0x16c
panic+0x188/0x498
__cfi_slowpath+0x0/0x214
__cfi_slowpath+0x1dc/0x214
spmi_drv_remove+0x16c/0x1e0
device_release_driver_internal+0x468/0x79c
driver_detach+0x11c/0x1a0
bus_remove_driver+0xc4/0x124
driver_unregister+0x58/0x84
cleanup_module+0x1c/0xc24 [qcom_spmi_pmic]
__do_sys_delete_module+0x3ec/0x53c
__arm64_sys_delete_module+0x18/0x28
el0_svc_common+0xdc/0x294
el0_svc+0x38/0x9c
el0_sync_handler+0x8c/0xf0
el0_sync+0x1b4/0x1c0

If a driver has all its resources allocated through devm_() APIs and
does not need any other explicit cleanup, it would not require a
remove callback to be defined. Hence, add a check for remove callback
presence before calling it when removing a SPMI driver.

Signed-off-by: Jishnu Prakash <[email protected]>
---
drivers/spmi/spmi.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/spmi/spmi.c b/drivers/spmi/spmi.c
index a456ce5..6b34356 100644
--- a/drivers/spmi/spmi.c
+++ b/drivers/spmi/spmi.c
@@ -350,7 +350,8 @@ static void spmi_drv_remove(struct device *dev)
const struct spmi_driver *sdrv = to_spmi_driver(dev->driver);

pm_runtime_get_sync(dev);
- sdrv->remove(to_spmi_device(dev));
+ if (sdrv->remove)
+ sdrv->remove(to_spmi_device(dev));
pm_runtime_put_noidle(dev);

pm_runtime_disable(dev);
--
2.7.4

2023-04-13 04:24:57

by Stephen Boyd

Subject: Re: [PATCH] spmi: Add a check for remove callback when removing a SPMI driver

Quoting Jishnu Prakash (2022-12-20 21:37:12)
> When removing a SPMI driver, there can be a crash due to NULL pointer
> dereference if it does not have a remove callback defined. This is
> one such call trace observed when removing the QCOM SPMI PMIC driver:
>
> dump_backtrace.cfi_jt+0x0/0x8
> dump_stack_lvl+0xd8/0x16c
> panic+0x188/0x498
> __cfi_slowpath+0x0/0x214
> __cfi_slowpath+0x1dc/0x214
> spmi_drv_remove+0x16c/0x1e0
> device_release_driver_internal+0x468/0x79c
> driver_detach+0x11c/0x1a0
> bus_remove_driver+0xc4/0x124
> driver_unregister+0x58/0x84
> cleanup_module+0x1c/0xc24 [qcom_spmi_pmic]
> __do_sys_delete_module+0x3ec/0x53c
> __arm64_sys_delete_module+0x18/0x28
> el0_svc_common+0xdc/0x294
> el0_svc+0x38/0x9c
> el0_sync_handler+0x8c/0xf0
> el0_sync+0x1b4/0x1c0
>
> If a driver has all its resources allocated through devm_() APIs and
> does not need any other explicit cleanup, it would not require a
> remove callback to be defined. Hence, add a check for remove callback
> presence before calling it when removing a SPMI driver.
>
> Signed-off-by: Jishnu Prakash <[email protected]>
> ---

Applied to spmi-next