On Thu, Jan 19, 2023 at 11:21:22AM -0500, Jeff Moyer wrote: > Dan Carpenter <error27@xxxxxxxxx> writes: > > > The concern here would be that "family" is negative and we pass a > > negative value to test_bit() resulting in an out of bounds read > > and potentially a crash. > > I don't see how this can happen. Do you have a particular scenario in > mind? > This is from static analysis. My main thinking was: 1) The static checker says that this comes from the user. 2) Every upper bounds check should have a lower bounds check. 3) family is passed to array_index_nospec() so we must not trust it. But looking closer today here is what the checker is concerned about: func = cmd_to_func(nfit_mem, cmd, call_pkg, &family); Assume "nfit_mem" is NULL but "call_pkg" is non NULL (user input from __nd_ioctl() or ars_get_status(). In that case family is unchecked user input. But probably, it's not possible for nfit_mem to be NULL in those caller functions? regards, dan carpenter
