On Mon, 24 Jan 2022 14:32:26 -0800
Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> On 1/24/22 14:21, Denis Pauk wrote:
> > On Sun, 23 Jan 2022 18:32:48 -0800
> > Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> >
> >> Paweł Marciniak reports the following crash, observed when clearing
> >> the chassis intrusion alarm.
> >>
> >> BUG: kernel NULL pointer dereference, address: 0000000000000028
> >> PGD 0 P4D 0
> >> Oops: 0000 [#1] PREEMPT SMP PTI
> >> CPU: 3 PID: 4815 Comm: bash Tainted: G S
> >> 5.16.2-200.fc35.x86_64 #1 Hardware name: To Be Filled By O.E.M. To
> >> Be Filled By O.E.M./Z97 Extreme4, BIOS P2.60A 05/03/2018 RIP:
> >> 0010:clear_caseopen+0x5a/0x120 [nct6775] Code: 68 70 e8 e9 32 b1 e3
> >> 85 c0 0f 85 d2 00 00 00 48 83 7c 24 ... RSP: 0018:ffffabcb02803dd8
> >> EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000002 RCX:
> >> 0000000000000000 RDX: ffff8e8808192880 RSI: 0000000000000000 RDI:
> >> ffff8e87c7509a68 RBP: 0000000000000000 R08: 0000000000000001 R09:
> >> 000000000000000a R10: 000000000000000a R11: f000000000000000 R12:
> >> 000000000000001f R13: ffff8e87c7509828 R14: ffff8e87c7509a68 R15:
> >> ffff8e88494527a0 FS: 00007f4db9151740(0000)
> >> GS:ffff8e8ebfec0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000
> >> ES: 0000 CR0: 0000000080050033 CR2: 0000000000000028 CR3:
> >> 0000000166b66001 CR4: 00000000001706e0 Call Trace:
> >> <TASK>
> >> kernfs_fop_write_iter+0x11c/0x1b0
> >> new_sync_write+0x10b/0x180
> >> vfs_write+0x209/0x2a0
> >> ksys_write+0x4f/0xc0
> >> do_syscall_64+0x3b/0x90
> >> entry_SYSCALL_64_after_hwframe+0x44/0xae
> >>
> >> The problem is that the device passed to clear_caseopen() is the
> >> hwmon device, not the platform device, and the platform data is
> >> not set in the hwmon device. Store the pointer to sio_data in
> >> struct nct6775_data and get if from there if needed.
> >>
> >> Fixes: 2e7b9886968b ("hwmon: (nct6775) Use superio_*() function
> >> pointers in sio_data.") Cc: Denis Pauk <pauk.denis@xxxxxxxxx>
> >> Cc: Bernhard Seibold <mail@xxxxxxxxxxxxxxxxxxx>
> >> Reported-by: Paweł Marciniak <pmarciniak@xxxxxxxxxxxx>
> >> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> >> ---
> >> drivers/hwmon/nct6775.c | 6 +++---
> >> 1 file changed, 3 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/drivers/hwmon/nct6775.c b/drivers/hwmon/nct6775.c
> >> index fd3f91cb01c6..098d12b9ecda 100644
> >> --- a/drivers/hwmon/nct6775.c
> >> +++ b/drivers/hwmon/nct6775.c
> >> @@ -1175,7 +1175,7 @@ static inline u8 in_to_reg(u32 val, u8 nr)
> >>
> >> struct nct6775_data {
> >> int addr; /* IO base of hw monitor block */
> >> - int sioreg; /* SIO register address */
> >> + struct nct6775_sio_data *sio_data;
> >> enum kinds kind;
> > What do you think about remove kind field also from struct
> > nct6775_data? Code has copy of this field inside of the struct
> > nct6775_sio_data.
>
> I thought about it, but it would add a level of indirection to
> each access, and it is used for each register access (through
> is_word_sized). That would make the change pretty expensive
> in terms of runtime cost.
>
I see, thank you.
> Guenter
>
> >> const char *name;
> >>
> >> @@ -3559,7 +3559,7 @@ clear_caseopen(struct device *dev, struct
> >> device_attribute *attr, const char *buf, size_t count)
> >> {
> >> struct nct6775_data *data = dev_get_drvdata(dev);
> >> - struct nct6775_sio_data *sio_data = dev_get_platdata(dev);
> >> + struct nct6775_sio_data *sio_data = data->sio_data;
> >> int nr = to_sensor_dev_attr(attr)->index -
> >> INTRUSION_ALARM_BASE; unsigned long val;
> >> u8 reg;
> >> @@ -3967,7 +3967,7 @@ static int nct6775_probe(struct
> >> platform_device *pdev) return -ENOMEM;
> >>
> >> data->kind = sio_data->kind;
> >> - data->sioreg = sio_data->sioreg;
> >> + data->sio_data = sio_data;
> >>
> >> if (sio_data->access == access_direct) {
> >> data->addr = res->start;
> >
> > Tested-by: Denis Pauk <pauk.denis@xxxxxxxxx>
> >
> > Best regards,
> > Denis.
>
Best regards,
Denis.
