On 30/08/2024 17:42, Gregory Price wrote:
> On Fri, Aug 30, 2024 at 10:28:52PM +0100, Usama Arif wrote:
>> If efi.tpm_log is corrupted, log_tbl->size can be garbage (and
>> negative). This can result in a large memblock reservation, resulting
>> in the kernel booting without sufficient memory. Move the memblock
>> reservation after log_tbl->version check, and check the value of
>> both tbl_size and memblock_reserve.
>>
>> Signed-off-by: Usama Arif <usamaarif642@xxxxxxxxx>
>> ---
>> drivers/firmware/efi/tpm.c | 16 +++++++++++++---
>> 1 file changed, 13 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/firmware/efi/tpm.c b/drivers/firmware/efi/tpm.c
>> index e8d69bd548f3..cfc6a065f441 100644
>> --- a/drivers/firmware/efi/tpm.c
>> +++ b/drivers/firmware/efi/tpm.c
>> @@ -59,9 +59,6 @@ int __init efi_tpm_eventlog_init(void)
>> return -ENOMEM;
>> }
>>
>> - tbl_size = sizeof(*log_tbl) + log_tbl->size;
>> - memblock_reserve(efi.tpm_log, tbl_size);
>> -
>> if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR) {
>> pr_info("TPM Final Events table not present\n");
>> goto out;
>
> The final event table is not present in TCG 1_2 format, but the
> tpm log still needs to be mapped. So this change is incorrect for
> v1_2.
hmm so we have
if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR) {
pr_info("TPM Final Events table not present\n");
goto out;
} else if (log_tbl->version != EFI_TCG2_EVENT_LOG_FORMAT_TCG_2) {
pr_warn(FW_BUG "TPM Final Events table invalid\n");
goto out;
}
If the format is TCG 1_2, then log_tbl is not used?
>
>> @@ -70,6 +67,19 @@ int __init efi_tpm_eventlog_init(void)
>> goto out;
>> }
>>
>> + tbl_size = sizeof(*log_tbl) + log_tbl->size;
>> + if (tbl_size < 0) {
>> + pr_err(FW_BUG "Failed to parse event in TPM Final Events Log\n");
>> + ret = -EINVAL;
>> + goto out;
>> + }
>> + if (memblock_reserve(efi.tpm_log, tbl_size)) {
>> + pr_err("TPM Event Log memblock reserve fails 0x%lx - %x\n",
>> + efi.tpm_log, tbl_size);
>> + ret = -ENOMEM;
>> + goto out;
>> + }
>> +
>> final_tbl = early_memremap(efi.tpm_final_log, sizeof(*final_tbl));
>>
>> if (!final_tbl) {
>> --
>> 2.43.5
>>
