| Message ID | 20240430142434.10471-13-Jonathan.Cameron@huawei.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere, archived |
| Headers | show |
| Series | ACPI/arm64: add support for virtual cpu hotplug | expand |
On 5/1/24 00:24, Jonathan Cameron wrote: > In a review discussion of the changes to support vCPU hotplug where > a check was added on the GICC being enabled if was was online, it was ^^^^^^^ typo > noted that there is need to map back to the cpu and use that to index > into a cpumask. As such, a valid ID is needed. > > If an MPIDR check fails in acpi_map_gic_cpu_interface() it is possible > for the entry in cpu_madt_gicc[cpu] == NULL. This function would > then cause a NULL pointer dereference. Whilst a path to trigger > this has not been established, harden this caller against the > possibility. > > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > --- > v9: New patch in response to a question from Marc Zyngier. > Taking the easy way out - harden against a possible condition rather > than establishing it never happens! > --- > arch/arm64/include/asm/acpi.h | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > With the typo corrected: Reviewed-by: Gavin Shan <gshan@redhat.com> > diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h > index bc9a6656fc0c..a407f9cd549e 100644 > --- a/arch/arm64/include/asm/acpi.h > +++ b/arch/arm64/include/asm/acpi.h > @@ -124,7 +124,8 @@ static inline int get_cpu_for_acpi_id(u32 uid) > int cpu; > > for (cpu = 0; cpu < nr_cpu_ids; cpu++) > - if (uid == get_acpi_id_for_cpu(cpu)) > + if (acpi_cpu_get_madt_gicc(cpu) && > + uid == get_acpi_id_for_cpu(cpu)) > return cpu; > > return -EINVAL;
diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h index bc9a6656fc0c..a407f9cd549e 100644 --- a/arch/arm64/include/asm/acpi.h +++ b/arch/arm64/include/asm/acpi.h @@ -124,7 +124,8 @@ static inline int get_cpu_for_acpi_id(u32 uid) int cpu; for (cpu = 0; cpu < nr_cpu_ids; cpu++) - if (uid == get_acpi_id_for_cpu(cpu)) + if (acpi_cpu_get_madt_gicc(cpu) && + uid == get_acpi_id_for_cpu(cpu)) return cpu; return -EINVAL;
In a review discussion of the changes to support vCPU hotplug where a check was added on the GICC being enabled if was was online, it was noted that there is need to map back to the cpu and use that to index into a cpumask. As such, a valid ID is needed. If an MPIDR check fails in acpi_map_gic_cpu_interface() it is possible for the entry in cpu_madt_gicc[cpu] == NULL. This function would then cause a NULL pointer dereference. Whilst a path to trigger this has not been established, harden this caller against the possibility. Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> --- v9: New patch in response to a question from Marc Zyngier. Taking the easy way out - harden against a possible condition rather than establishing it never happens! --- arch/arm64/include/asm/acpi.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)