Re: [PATCH] ACPI: GTDT: Tighten the check for the first platform timer entry

[Zheng Zengkai]

在 2024/10/10 23:52, Marc Zyngier 写道:
> On Thu, 10 Oct 2024 15:47:03 +0100,
> Zheng Zengkai <zhengzengkai@xxxxxxxxxx> wrote:
> > As suggested by Marc and Lorenzo, first we need to check whether
> > the platform_timer pointer is within gtdt bounds (< gtdt_end) before
> > de-referencing what it points at to detect the (first) platform
> > timer entry length and check that next platform_timer pointer is
> > within gtdt_end too. Now we do that only in next_platform_timer()
> > for subsequent platform timers.
> >
> > So add check against table length (gtdt_end) for the first platform
> > timer entry.
> >
> > Suggested-by: Marc Zyngier <maz@xxxxxxxxxx>
> > Suggested-by: Lorenzo Pieralisi <lpieralisi@xxxxxxxxxx>
> > Signed-off-by: Zheng Zengkai <zhengzengkai@xxxxxxxxxx>
> > ---
> >   drivers/acpi/arm64/gtdt.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/acpi/arm64/gtdt.c b/drivers/acpi/arm64/gtdt.c
> > index c0e77c1c8e09..f249af1ed1cd 100644
> > --- a/drivers/acpi/arm64/gtdt.c
> > +++ b/drivers/acpi/arm64/gtdt.c
> > @@ -177,7 +177,8 @@ int __init acpi_gtdt_init(struct acpi_table_header *table,
> >   	}
> >   
> >   	platform_timer = (void *)gtdt + gtdt->platform_timer_offset;
> > -	if (platform_timer < (void *)table + sizeof(struct acpi_table_gtdt)) {
> > +	if (platform_timer < (void *)table + sizeof(struct acpi_table_gtdt) ||
> > +			platform_timer >= acpi_gtdt_desc.gtdt_end) {
> >   		pr_err(FW_BUG "invalid timer data.\n");
> >   		return -EINVAL;
> >   	}
> You  are  only  checking  the  base  pointer  for  the  platform_timer
> array. This doesn't say anything about the *size* of that array (or at
> least its first element), and whether that actually fits in the table.
>
> 	M.


Yes, I will send v2 to check against gtdt_end for both entry and length

of each array element.

Thanks!