On Thu, Jan 19, 2023 at 11:21:22AM -0500, Jeff Moyer wrote:
> Dan Carpenter <[email protected]> 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
