On Thu, May 07, 2020 at 11:02:18AM -0700, Kees Cook wrote: > On Wed, May 06, 2020 at 11:09:12PM -0500, Gustavo A. R. Silva wrote: > > As mentioned above: "Flexible array members have incomplete type, and > > so the sizeof operator may not be applied. As a quirk of the original > > implementation of zero-length arrays, sizeof evaluates to zero."[1] So, > > the sizeof(flexible-array) can be safely removed to fix the error above. > > As in "sizeof(event_header->event) always evaluated to 0, so removing it > has no effect". >
Thanks for this. I wanted to make a more general statement, but I'll update the changelog text. :) > > [...] > > diff --git a/drivers/char/tpm/eventlog/tpm2.c > > b/drivers/char/tpm/eventlog/tpm2.c > > index e741b1157525..351a2989b3c6 100644 > > --- a/drivers/char/tpm/eventlog/tpm2.c > > +++ b/drivers/char/tpm/eventlog/tpm2.c > > @@ -51,8 +51,7 @@ static void *tpm2_bios_measurements_start(struct seq_file > > *m, loff_t *pos) > > int i; > > > > event_header = addr; > > - size = sizeof(struct tcg_pcr_event) - sizeof(event_header->event) > > - + event_header->event_size; > > + size = sizeof(*event_header) + event_header->event_size; > > That said, I think it would be better to stick to the struct_size() > idiom for dealing with flexible arrays here: > > size = struct_size(event_header, event, event_size); > Yep, I agree. I'll add this and send v2, shortly. Thanks -- Gustavo
