On Mon, Jan 24, 2022 at 12:19:03PM -0800, Kees Cook wrote: > On Fri, Jan 21, 2022 at 04:22:50PM -0600, Gustavo A. R. Silva wrote: > > Make use of the struct_size() helper instead of an open-coded version, > > in order to avoid any potential type mistakes or integer overflows that, > > in the worst scenario, could lead to heap overflows. > > > > Also, address the following sparse warnings: > > drivers/staging/greybus/i2c.c:111:24: warning: using sizeof on a flexible structure > > > > Link: https://github.com/KSPP/linux/issues/174 > > Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx> > > --- > > drivers/staging/greybus/i2c.c | 4 +--- > > 1 file changed, 1 insertion(+), 3 deletions(-) > > > > diff --git a/drivers/staging/greybus/i2c.c b/drivers/staging/greybus/i2c.c > > index de2f6516da09..9dfc6791c20e 100644 > > --- a/drivers/staging/greybus/i2c.c > > +++ b/drivers/staging/greybus/i2c.c > > @@ -108,9 +108,7 @@ gb_i2c_operation_create(struct gb_connection *connection, > > else > > data_out_size += (u32)msg->len; > > > > - request_size = sizeof(*request); > > - request_size += msg_count * sizeof(*op); > > - request_size += data_out_size; > > + request_size = struct_size(request, ops, msg_count) + data_out_size; > > This could still overflow if struct_size() returns SIZE_MAX. Perhaps: uggh... I got too excited with all the new cases reported. > > if (check_add_overflow(struct_size(request, ops, msg_count), > data_out_size, &request_size)) > request_size = SIZE_MAX; Yep; I'll respin and include this change, thanks! > > I should brush off the saturating arithmetic helpers series: > https://lore.kernel.org/all/20210920180853.1825195-1-keescook@xxxxxxxxxxxx/ Yeah; those helpers are very much needed in many places we need to audit... -- Gustavo
