Re: Possible broken MM code in dell-laptop.c?

Pali Rohár
2015-06-15T20:42:41Z

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On Monday 15 June 2015 22:36:45 Darren Hart wrote:
> On Sun, Jun 14, 2015 at 11:05:07AM +0200, Pali Rohár wrote:
> > Hello,
> >
> > in drivers/platform/x86/dell-laptop.c is this part of code:
> >
> > static int __init dell_init(void)
> > {
> > ...
> >
> > /*
> >
> > * Allocate buffer below 4GB for SMI data--only 32-bit physical
> > addr * is passed to SMI handler.
> > */
> >
> > bufferpage = alloc_page(GFP_KERNEL | GFP_DMA32);
> > if (!bufferpage) {
> >
> > ret = -ENOMEM;
> > goto fail_buffer;
> >
> > }
> > buffer = page_address(bufferpage);
> >
> > ret = dell_setup_rfkill();
> >
> > if (ret) {
> >
> > pr_warn("Unable to setup rfkill\n");
> > goto fail_rfkill;
> >
> > }
> >
> > ...
> >
> > fail_rfkill:
> > free_page((unsigned long)bufferpage);
> >
> > fail_buffer:
> > ...
> > }
> >
> > Then there is another part:
> >
> > static void __exit dell_exit(void)
> > {
> > ...
> >
> > free_page((unsigned long)buffer);
>
> I believe you are correct, and this should be bufferpage. Have you
> observed any failures?

Rmmoding dell-laptop.ko works fine. There is no error in dmesg. I think
that buffer (and not bufferpage) should be passed to free_page(). So in
my opinion problem is at fail_rfkill: label and not in dell_exit().

But somebody from linux-mm should look at it...

--
Pali Rohár
pali.rohar@gmail.com

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