Re: [PATCH 1/3] dell-laptop: Clear buffer before each SMBIOS call

Pali Rohár
2015-07-03T08:10:58Z

On Wednesday 01 July 2015 17:45:44 Darren Hart wrote:
> On Wed, Jul 01, 2015 at 08:08:19PM +0200, Pali Rohár wrote:
> > Make sure that before initializing SMBIOS call input buffer does not contain
> > any garbage (e.g values from previous SMBIOS call). This fix problem with
> > passing undefined/random parameters to SMBIOS functions.
> >
> > Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
> > ---
> > drivers/platform/x86/dell-laptop.c | 11 ++++++++++-
> > 1 file changed, 10 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
> > index 35758cb..6728487 100644
> > --- a/drivers/platform/x86/dell-laptop.c
> > +++ b/drivers/platform/x86/dell-laptop.c
> > @@ -310,10 +310,15 @@ static DEFINE_MUTEX(buffer_mutex);
> >
> > static int hwswitch_state;
> >
> > +static void clear_buffer(void)
> > +{
> > + memset(buffer, 0, sizeof(struct calling_interface_buffer));
> > +}
> > +
> > static void get_buffer(void)
> > {
> > mutex_lock(&buffer_mutex);
> > - memset(buffer, 0, sizeof(struct calling_interface_buffer));
> > + clear_buffer();
> > }
> >
> > static void release_buffer(void)
> > @@ -557,6 +562,8 @@ static int dell_rfkill_set(void *data, bool blocked)
> > !(buffer->output[1] & BIT(16)))
> > disable = 1;
> >
> > + clear_buffer();
> > +
> > buffer->input[0] = (1 | (radio<<8) | (disable << 16));
> > dell_send_request(buffer, 17, 11);
> >
> > @@ -571,6 +578,7 @@ static void dell_rfkill_update_sw_state(struct rfkill *rfkill, int radio,
> > if (status & BIT(0)) {
> > /* Has hw-switch, sync sw_state to BIOS */
> > int block = rfkill_blocked(rfkill);
> > + clear_buffer();
> > buffer->input[0] = (1 | (radio << 8) | (block << 16));
> > dell_send_request(buffer, 17, 11);
> > } else {
> > @@ -774,6 +782,7 @@ static int __init dell_setup_rfkill(void)
> > dell_send_request(buffer, 17, 11);
> > status = buffer->output[1];
> > buffer->input[0] = 0x2;
> > + clear_buffer();
> > dell_send_request(buffer, 17, 11);
>
> This clears the buffer after modifying input[0] and right before
> dell_send_request... so you're sending a completely empty buffer? Is that
> intentional here? I guess I would have expected the clear_buffer to be one line
> earlier.
>

Yes, now I see. I split that one patch into tree and I checked that
every one compiles fine and cumulative change of all patches is same...
Because that part (sending 0x2) is deleted in patch 3/3 it missed in my
eyes...

I will fix these problems and sent patch series again.

> > hwswitch_state = buffer->output[1];
> > release_buffer();
> > --
> > 1.7.9.5
> >
> >
>

--
Pali Rohár
pali.rohar@gmail.com