7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mario Limonciello [ Upstream commit b7b273844b94af9cc64907dccd9e7997c2b60f1a ] amd_hfi_fill_metadata() parses CPU core ranking data out of the firmware-provided PCC shared memory but trusts two values it should not: - n_bitmaps is used to bound the outer loop that reads the APIC ID bitmaps from table_data[], but it is never validated against the size of the shared memory region (pcct_ext->length). A firmware-supplied count larger than the region reads past the end of table_data. - When resolving the base of the ranking data for a processor, the pointer is shifted by an extra "i * nr_class" term, where i is the current bitmap index. The per-processor offset is already applied through apic_index, which uses the running count of active processors (apic_start). The extra shift compounds for every logical processor beyond the first bitmap (APIC ID >= 32), reading out of bounds. Both result in out-of-bounds reads that can corrupt the ranking metrics, oops, or otherwise destabilise the system. Reject an n_bitmaps value that would not fit within the shared memory region, and drop the bogus "i * nr_class" term so the ranking data is addressed only through its correct per-processor offset. Cc: stable@vger.kernel.org Reported-by: Sashiko Fixes: d4e95ea7a78e ("platform/x86: hfi: Parse CPU core ranking data from shared memory") Signed-off-by: Mario Limonciello Link: https://patch.msgid.link/20260921170411.1149960-3-mario.limonciello@amd.com Signed-off-by: Ilpo Järvinen Signed-off-by: Sasha Levin --- drivers/platform/x86/amd/hfi/hfi.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/drivers/platform/x86/amd/hfi/hfi.c b/drivers/platform/x86/amd/hfi/hfi.c index e1c776b71f3e6..6d1d3b6c28a97 100644 --- a/drivers/platform/x86/amd/hfi/hfi.c +++ b/drivers/platform/x86/amd/hfi/hfi.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -168,6 +169,21 @@ static int amd_hfi_fill_metadata(struct amd_hfi_data *amd_hfi_data) return -EINVAL; } + /* + * The bitmaps enumerating the APIC IDs occupy the first n_bitmaps + * words of table_data. Reject a firmware-provided count that would + * push those reads past the end of the shared memory region. + */ + if (struct_size(amd_hfi_data->shmem, table_data, amd_hfi_data->shmem->n_bitmaps) > + pcct_ext->length) { + dev_err(amd_hfi_data->dev, "invalid number of bitmaps: %u\n", + amd_hfi_data->shmem->n_bitmaps); + return -EINVAL; + } + + /* The ranking data for each processor follows the bitmaps */ + u32 *table = amd_hfi_data->shmem->table_data + amd_hfi_data->shmem->n_bitmaps; + for (unsigned int i = 0; i < amd_hfi_data->shmem->n_bitmaps; i++) { u32 bitmap = amd_hfi_data->shmem->table_data[i]; @@ -192,10 +208,6 @@ static int amd_hfi_fill_metadata(struct amd_hfi_data *amd_hfi_data) info = per_cpu_ptr(&amd_hfi_cpuinfo, cpu_index); apic_index = apic_start * info->nr_class * 2; for (unsigned int k = 0; k < info->nr_class; k++) { - u32 *table = amd_hfi_data->shmem->table_data + - amd_hfi_data->shmem->n_bitmaps + - i * info->nr_class; - info->amd_hfi_classes[k].eff = table[apic_index + 2 * k]; info->amd_hfi_classes[k].perf = table[apic_index + 2 * k + 1]; } -- 2.53.0