Hi,
On 5/6/25 8:13 AM, Heyne, Maximilian wrote:
Commit 7ab4f0e37a0f ("ACPI PPTT: Fix coding mistakes in a couple of sizeof() calls") corrects the processer entry size but unmasked a longer standing bug where the last entry in the structure can get skipped due to an off-by-one mistake if the last entry ends exactly at the end of the ACPI subtable.
The error manifests for instance on EC2 Graviton Metal instances with
ACPI PPTT: PPTT table found, but unable to locate core 63 (63) [...] ACPI: SPE must be homogeneous
Fixes: 2bd00bcd73e5 ("ACPI/PPTT: Add Processor Properties Topology Table parsing") Cc: stable@vger.kernel.org Signed-off-by: Maximilian Heyne mheyne@amazon.de
drivers/acpi/pptt.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c index f73ce6e13065d..4364da90902e5 100644 --- a/drivers/acpi/pptt.c +++ b/drivers/acpi/pptt.c @@ -231,7 +231,7 @@ static int acpi_pptt_leaf_node(struct acpi_table_header *table_hdr, sizeof(struct acpi_table_pptt)); proc_sz = sizeof(struct acpi_pptt_processor);
This isn't really right, it should be struct acpi_subtable_header, then once the header is safe, pull the length from it.
But then, really if we are trying to fix the original bug that the table could be shorter than the data in it suggests, the struct acpi_pptt_processor length plus its resources needs to be checked once the subtype is known to be a processor node.
Otherwise the original sizeof * change isn't really fixing anything.
- while ((unsigned long)entry + proc_sz < table_end) {
- while ((unsigned long)entry + proc_sz <= table_end) { cpu_node = (struct acpi_pptt_processor *)entry; if (entry->type == ACPI_PPTT_TYPE_PROCESSOR && cpu_node->parent == node_entry)
@@ -273,7 +273,7 @@ static struct acpi_pptt_processor *acpi_find_processor_node(struct acpi_table_he proc_sz = sizeof(struct acpi_pptt_processor); /* find the processor structure associated with this cpuid */
- while ((unsigned long)entry + proc_sz < table_end) {
- while ((unsigned long)entry + proc_sz <= table_end) { cpu_node = (struct acpi_pptt_processor *)entry;
if (entry->length == 0) {