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.
> @@ -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
>
