LinuxLists.cc - [PATCH] driver core: bus: Handle early calls to bus_to

2023-02-21 12:54:21

Subject: [PATCH] driver core: bus: Handle early calls to bus_to_subsys()

When calling soc_device_match() from early_initcall(), bus_kset is still
NULL, causing a crash:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000028
...
Call trace:
__lock_acquire+0x530/0x20f0
lock_acquire.part.0+0xc8/0x210
lock_acquire+0x64/0x80
_raw_spin_lock+0x4c/0x60
bus_to_subsys+0x24/0xac
bus_for_each_dev+0x30/0xcc
soc_device_match+0x4c/0xe0
r8a7795_sysc_init+0x18/0x60
rcar_sysc_pd_init+0xb0/0x33c
do_one_initcall+0x128/0x2bc

Before, bus_for_each_dev() handled this gracefully by checking that
the back-pointer to the private structure was valid.

Fix this by adding a NULL check for bus_kset to bus_to_subsys().

Fixes: 83b9148df2c95e23 ("driver core: bus: bus iterator cleanups")
Signed-off-by: Geert Uytterhoeven <[email protected]>
---
drivers/base/bus.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index cfe8615d5106f030..dd4b82d7510f68fb 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -62,7 +62,7 @@ static struct subsys_private *bus_to_subsys(const struct bus_type *bus)
struct subsys_private *sp = NULL;
struct kobject *kobj;

- if (!bus)
+ if (!bus || !bus_kset)
return NULL;

spin_lock(&bus_kset->list_lock);
--
2.34.1

2023-02-21 13:48:02

by Greg Kroah-Hartman

[permalink] [raw]

Subject: Re: [PATCH] driver core: bus: Handle early calls to bus_to_subsys()

On Tue, Feb 21, 2023 at 01:53:51PM +0100, Geert Uytterhoeven wrote:
> When calling soc_device_match() from early_initcall(), bus_kset is still
> NULL, causing a crash:
>
> Unable to handle kernel NULL pointer dereference at virtual address 0000000000000028
> ...
> Call trace:
> __lock_acquire+0x530/0x20f0
> lock_acquire.part.0+0xc8/0x210
> lock_acquire+0x64/0x80
> _raw_spin_lock+0x4c/0x60
> bus_to_subsys+0x24/0xac
> bus_for_each_dev+0x30/0xcc
> soc_device_match+0x4c/0xe0
> r8a7795_sysc_init+0x18/0x60
> rcar_sysc_pd_init+0xb0/0x33c
> do_one_initcall+0x128/0x2bc
>
> Before, bus_for_each_dev() handled this gracefully by checking that
> the back-pointer to the private structure was valid.
>
> Fix this by adding a NULL check for bus_kset to bus_to_subsys().
>
> Fixes: 83b9148df2c95e23 ("driver core: bus: bus iterator cleanups")
> Signed-off-by: Geert Uytterhoeven <[email protected]>
> ---
> drivers/base/bus.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/base/bus.c b/drivers/base/bus.c
> index cfe8615d5106f030..dd4b82d7510f68fb 100644
> --- a/drivers/base/bus.c
> +++ b/drivers/base/bus.c
> @@ -62,7 +62,7 @@ static struct subsys_private *bus_to_subsys(const struct bus_type *bus)
> struct subsys_private *sp = NULL;
> struct kobject *kobj;
>
> - if (!bus)
> + if (!bus || !bus_kset)
> return NULL;
>
> spin_lock(&bus_kset->list_lock);

Thanks for this, I'll queue it up after my patches get sent to Linus.

greg k-h

2023-02-28 10:58:03

by Wolfram Sang

[permalink] [raw]

Subject: Re: [PATCH] driver core: bus: Handle early calls to bus_to_subsys()

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2023-03-02 10:20:48

by Greg Kroah-Hartman

[permalink] [raw]

Subject: Re: [PATCH] driver core: bus: Handle early calls to bus_to_subsys()

On Tue, Feb 28, 2023 at 11:57:02AM +0100, Wolfram Sang wrote:
> On Tue, Feb 21, 2023 at 01:53:51PM +0100, Geert Uytterhoeven wrote:
> > When calling soc_device_match() from early_initcall(), bus_kset is still
> > NULL, causing a crash:
> >
> > Unable to handle kernel NULL pointer dereference at virtual address 0000000000000028
> > ...
> > Call trace:
> > __lock_acquire+0x530/0x20f0
> > lock_acquire.part.0+0xc8/0x210
> > lock_acquire+0x64/0x80
> > _raw_spin_lock+0x4c/0x60
> > bus_to_subsys+0x24/0xac
> > bus_for_each_dev+0x30/0xcc
> > soc_device_match+0x4c/0xe0
> > r8a7795_sysc_init+0x18/0x60
> > rcar_sysc_pd_init+0xb0/0x33c
> > do_one_initcall+0x128/0x2bc
> >
> > Before, bus_for_each_dev() handled this gracefully by checking that
> > the back-pointer to the private structure was valid.
> >
> > Fix this by adding a NULL check for bus_kset to bus_to_subsys().
> >
> > Fixes: 83b9148df2c95e23 ("driver core: bus: bus iterator cleanups")
> > Signed-off-by: Geert Uytterhoeven <[email protected]>
>
> Current top-of-head doesn't boot my Salvator-XS board, this patch fixed
> it.
>
> Tested-by: Wolfram Sang <[email protected]>
>

Great, now sent to Linus.

greg k-h