[PATCH v4] tpm: Managed allocations for tpm_buf instances

[James Bottomley]

On Tue, 2025-07-01 at 17:51 +0300, Jarkko Sakkinen wrote:
> Repeal and replace tpm_buf_init() and tpm_buf_init_sized() with
> tpm_buf_alloc(), which returns a buffer of  memory with the struct
> tpm_buf header at the beginning of the returned buffer. This leaves
> 4090 bytes of free space for the payload.

Shouldn't this be accounted for in tpm_buf_append()? right now it will
let us run off the end of the allocation by six bytes before it signals
overflow because it's checking final length against PAGE_SIZE not
PAGE_SIZE - sizeof(struct tpm_buf).  I realise this should be an
impossible condition in production, but it's useful for debugging so we
should be accurate about it to avoid hard to detect bugs.

Regards,

James