> On Fri, 08 Nov 2024 09:48:38 +0100,
> Liang, Andy (Linux Ecosystem Engineering) wrote:
> >
> >
> > > On Thu, 07 Nov 2024 20:31:37 +0100,
> > > Stefan Berger wrote:
> > > >
> > > >
> > > >
> > > > On 11/7/24 2:06 PM, Stefan Berger wrote:
> > > > >
> > > > >
> > > > > On 11/7/24 7:38 AM, Takashi Iwai wrote:
> > > > >> On Thu, 07 Nov 2024 13:17:33 +0100, Paul Menzel wrote:
> > >> >>>
> > >> >>> Dear Takashi,
> > >> >>>
> > >> >>>
> > >> >>> Thank you for the patch.
> > >> >>>
> > >> >>> Am 07.11.24 um 12:18 schrieb Takashi Iwai:
> > >> >>>> The TPM2 ACPI table may request a large size for the event
> > >> log, >>>> and it may be over the max size of kmalloc(). When this
> > >> happens, >>>> the driver >>> >>> What is kmalloc()ʼs maximum
> > >> size?
> > >> >>
> > >> >> 128kB or so, IIRC.
> > >> >> And according Andy, the table can be over 4MB.
> > >> >
> > >> > Can you copy the contents of the file on that machine and tell
> > >> us > what size it has:
> > >> >
> > >> > cp /sys/kernel/security/tpm0/binary_bios_measurements ./
> > >>
> > >> Actually, you may need to have the contents parsed by a user space
> > >> tool since the driver does not detect where the actual end may be:
> > >>
> > >> tsseventextend -if ./binary_bios_measurements -sim -v
> > >>
> > >> This may give you a feeling for how much is in that file and then
> > >> you'd have to truncate it into half for example and see whether it
> > >> still parses the same. My point is that we haven't seen such
> > >> excessive-sized logs so far and following the parsing above we may
> > >> find something like this more useful than allocating possibly large
> > >> amounts of memory that a buggy ACPI table indicates (+ notify
> > >> manufacturer):
> > >>
> > >> if (len > MAX_TPM_LOG_SIZE) {
> > >> dev_err(&chip->dev, "Truncated excessive-sized TPM log of %d
> > >> bytes\n", len);
> > >> len = MAX_TPM_LOG_SIZE;
> > >> }
> > >>
> > >> If you send me the log I'd look at it.
> >
> > > It's rather a question Andy; could you check give the requested info?
> >
> >
> > https://elixir.bootlin.com/linux/v6.8/source/arch/x86/include/asm/page
> > _types.h#L10
> > #define PAGE_SHIFT 12
> > #define KMALLOC_SHIFT_MAX (MAX_PAGE_ORDER + PAGE_SHIFT)
> >
> > https://elixir.bootlin.com/linux/v6.8/source/include/linux/mmzone.h#L3
> > 0
> > #define MAX_PAGE_ORDER 10
> >
> > https://elixir.bootlin.com/linux/v6.8/source/include/linux/slab.h#L309
> > #define KMALLOC_MAX_SIZE (1UL << KMALLOC_SHIFT_MAX) The max size =
> > (1UL << MAX_PAGE_ORDER + PAGE_SHIFT) = ( 1UL << (10 + 12)) = 2^22
> > =4,194,304 (4MB)
> >
> > For the x86, the max size is 4MB.
>
> Thanks, it was already corrected by Jarkko :) But what I meant was about the requests:
>
> > cp /sys/kernel/security/tpm0/binary_bios_measurements ./
>
> and
>
> > tsseventextend -if ./binary_bios_measurements -sim -v
>
> mentioned in the above. Could you provide the info?
Please check the attached file. The file has also been uploaded to the SUSE Bugzilla.
Thank you.
> thanks,
>
> Takashi
