On 2020/12/8 21:28, Dan Carpenter wrote:
> Hi Zhang,
>
> Are you using Coccinelle to detect these bugs?
In fact, I'm not familiar with Coccinelle, these bugs are reported by robot.
>
> On Sat, Dec 05, 2020 at 02:32:50PM -0800, Jakub Kicinski wrote:
>> Hi!
>>
>> Recently we've been getting a steady stream of patches from Changzhong
>> to fix missing assignment to error variables before jumping to error
>> cases.
>
> I've mucked about with this a little in Smatch trying to work out some
> heuristics to use. I added a warning for a NULL return followed by a
> goto. Then on Friday I added a warning for a _dev_err() print followed
> by a goto. But neither of those rules catches the bug fixed by commit
> 4de377b65903 ("net: marvell: prestera: Fix error return code in
> prestera_port_create()"), where the error was invalid data.
>
> if (idx >= size)
> goto free_whatever;
>
> I'm going to print a warning if the function ends in a cleanup block
> that can only be reached by gotos. We'll see how that works tomorrow.
>
> static void match_return(struct statement *stmt)
> {
> struct sm_state *sm, *tmp;
> sval_t sval;
> char *name;
> bool is_last;
>
> // Only complain if the function returns a variable
> if (!stmt->ret_value || stmt->ret_value->type != EXPR_SYMBOL)
> return;
>
> // The function returns an int
> if (cur_func_return_type() != &int_ctype)
> return;
>
> // It's only reachable via a goto
> if (get_state(my_id, "path", NULL) != &label)
> return;
>
> // It returns a negative error code
> sm = get_extra_sm_state(stmt->ret_value);
> if (!sm || !estate_rl(sm->state) ||
> !sval_is_negative(rl_min(estate_rl(sm->state))))
> return;
>
> FOR_EACH_PTR(sm->possible, tmp) {
> // There is at least one path where "ret" is zero
> if (estate_get_single_value(tmp->state, &sval) &&
> sval.value == 0)
> goto warn;
> } END_FOR_EACH_PTR(tmp);
>
> return;
> warn:
> // It's the last statement of a function
> is_last = is_last_stmt(stmt);
>
> name = expr_to_str(stmt->ret_value);
> sm_warning("missing error code '%s' rl='%s' is_last=%d", name, sm->state->name, is_last);
> free_string(name);
> }
>
> regards,
> dan carpenter
>
> .
>
