On Thu, May 21, 2026 at 11:36:39AM +0200, Thorsten Blum wrote:
> Commit 186d124f07da ("tpm_eventlog.c: fix binary_bios_measurements")
> split the output to write the endian-converted event header first and
> then the variable-length event data.
>
> However, the split was at sizeof(struct tcpa_event) - 1, even though
> event_data was a zero-length array, and later a flexible array member,
> both of which already excluded the event data.
>
> Therefore, the current code writes the first three bytes of event_size
> from the endian-converted header and then the last byte from the raw
> header, which can emit a corrupted event_size on PPC64, where
> do_endian_conversion() maps to be32_to_cpu().
>
> Use seq_write() to write the full endian-converted header, followed by
> the variable-length event->event_data.
>
> Drop the obvious comment while at it.
>
> Fixes: 186d124f07da ("tpm_eventlog.c: fix binary_bios_measurements")
> Cc: [email protected]
> Signed-off-by: Thorsten Blum <[email protected]>
> ---
> drivers/char/tpm/eventlog/tpm1.c | 16 ++--------------
> 1 file changed, 2 insertions(+), 14 deletions(-)
Got it, I think you're probably right.
>
> diff --git a/drivers/char/tpm/eventlog/tpm1.c
> b/drivers/char/tpm/eventlog/tpm1.c
> index e7913b2853d5..291720e89d91 100644
> --- a/drivers/char/tpm/eventlog/tpm1.c
> +++ b/drivers/char/tpm/eventlog/tpm1.c
> @@ -224,29 +224,17 @@ static int tpm1_binary_bios_measurements_show(struct
> seq_file *m, void *v)
> {
> struct tcpa_event *event = v;
> struct tcpa_event temp_event;
> - char *temp_ptr;
> - int i;
>
> memcpy(&temp_event, event, sizeof(struct tcpa_event));
>
> - /* convert raw integers for endianness */
spurious change
> temp_event.pcr_index = do_endian_conversion(event->pcr_index);
> temp_event.event_type = do_endian_conversion(event->event_type);
> temp_event.event_size = do_endian_conversion(event->event_size);
>
> - temp_ptr = (char *) &temp_event;
> -
> - for (i = 0; i < (sizeof(struct tcpa_event) - 1) ; i++)
> - seq_putc(m, temp_ptr[i]);
Why changing condition does not fix the bug? This could be just +-1 line
change.
> -
> - temp_ptr = (char *) v;
> -
> - for (i = (sizeof(struct tcpa_event) - 1);
> - i < (sizeof(struct tcpa_event) + temp_event.event_size); i++)
> - seq_putc(m, temp_ptr[i]);
> + seq_write(m, &temp_event, sizeof(temp_event));
> + seq_write(m, event->event_data, temp_event.event_size);
>
> return 0;
> -
> }
>
> static int tpm1_ascii_bios_measurements_show(struct seq_file *m, void *v)
BR, Jarkko
