On Sun, Sep 11, 2016 at 10:05:46PM -0600, Jason Gunthorpe wrote: > On Sun, Sep 11, 2016 at 03:19:00PM +0300, Jarkko Sakkinen wrote: > > tpm_write() does not check whether the buffer has at least enough space > > for the header before passing it to tpm_transmit() so an overflow can > > happen. > > Eh? > > tpm_write uses a hard wired buffer size of TPM_BUFSIZE when working > with tpm_transmit. > > in_size is never used except for the copy. We should probably fix that > to sanity check the header length vs in_size. > > That doesn't seem to be a security issue however because the header > length is propery limited to TPM_BUFSIZE and the data buffer is > allocated specifically for that process using kzalloc.
I was working on something else when I bumped into this. The commit message is not the best possible but still the issue is valid although it does not cause any imaginable harm because there is always TPM_BUFSIZE of room in the buffer passed by tpm_write. I'll update the commit message not to speak about tpm_write. "tpm_transmit() does not check whether the bufsiz can contain the TPM header. Add check for this and return -EINVAL if it the buffer is too small." The check should be in tpm_transmit() and also the commit message should be only about that. > Jason /Jarkko
