Re: [PATCH 4/4] kconfig: prevent out-of-bounds user input for numeric options

[Julian Braha <julianbraha@gmail.com>]

On 9/5/26 00:25, Nathan Chancellor wrote:
>> diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
>> index 4234a51d16fd..2227d89d6328 100644
>> --- a/scripts/kconfig/confdata.c
>> +++ b/scripts/kconfig/confdata.c
>> @@ -354,6 +354,12 @@ static int conf_set_sym_val(struct symbol *sym, int def, int def_flags, char *p)
>>  	case S_INT:
>>  	case S_HEX:
>>  		if (sym_string_valid(sym, p)) {
>> +			if (def != S_DEF_AUTO &&
>> +			    !sym_string_check_bounds(sym, p))
>> +				/* hex uses 64-bit unsigned integer */
>> +				conf_warning("value '%s' for %s is outside the 64-bit %s integer bounds",
>> +					     p, sym->name,
>> +					     sym->type == S_INT ? "signed" : "unsigned");
>>  			sym->def[def].val = xstrdup(p);
>>  			sym->flags |= def_flags;
>>  		} else {
> ...
>> diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
>> index 2d8b0c65ce1e..6f99216ee76d 100644
>> --- a/scripts/kconfig/menu.c
>> +++ b/scripts/kconfig/menu.c
>> @@ -4,7 +4,6 @@
>>   */
>>  
>>  #include <ctype.h>
>> -#include <errno.h>
>>  #include <stdarg.h>
>>  #include <stdlib.h>
>>  #include <string.h>
>> @@ -255,17 +254,13 @@ static int menu_validate_number(struct symbol *sym, struct symbol *sym2,
>>  		return 1;
>>  	}
>>  
>> -	errno = 0;
>> -	if (sym->type == S_INT) {
>> +	if (sym->type == S_INT)
>>  		type_bounds = "64-bit signed integer";
>> -		strtoll(sym2->name, NULL, 10);
>> -	} else {
>> +	else
>>  		/* hex */
>>  		type_bounds = "64-bit unsigned integer";
>> -		strtoull(sym2->name, NULL, 16);
>> -	}
>>  
>> -	if (errno == ERANGE) {
>> +	if (!sym_string_check_bounds(sym, sym2->name)) {
>>  		fprintf(stderr,
>>  			"%s:%d: error: %s constant '%s' is outside the %s bounds\n",
>>  			prop->filename, prop->lineno, sym_type_name(sym->type),
> 
> With this, you could inline the type bounds string like you did above:
> 
> diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
> index 6f99216ee76d..f4b5b11991b4 100644
> --- a/scripts/kconfig/menu.c
> +++ b/scripts/kconfig/menu.c
> @@ -238,8 +238,6 @@ void menu_add_symbol(enum prop_type type, struct symbol *sym, struct expr *dep)
>  static int menu_validate_number(struct symbol *sym, struct symbol *sym2,
>  				const struct property *prop)
>  {
> -	const char *type_bounds;
> -
>  	if (sym->type != S_INT && sym->type != S_HEX)
>  		return 0;
>  
> @@ -254,17 +252,11 @@ static int menu_validate_number(struct symbol *sym, struct symbol *sym2,
>  		return 1;
>  	}
>  
> -	if (sym->type == S_INT)
> -		type_bounds = "64-bit signed integer";
> -	else
> -		/* hex */
> -		type_bounds = "64-bit unsigned integer";
> -
>  	if (!sym_string_check_bounds(sym, sym2->name)) {
>  		fprintf(stderr,
> -			"%s:%d: error: %s constant '%s' is outside the %s bounds\n",
> +			"%s:%d: error: %s constant '%s' is outside the 64-bit %s integer bounds\n",
>  			prop->filename, prop->lineno, sym_type_name(sym->type),
> -			sym2->name, type_bounds);
> +			sym2->name, sym->type == S_INT ? "signed" : "unsigned");
>  
>  		return 1;
>  	}
> 
>> diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c
>> index 7e81b3676ee9..2d1c021fa395 100644
>> --- a/scripts/kconfig/symbol.c
>> +++ b/scripts/kconfig/symbol.c
>> @@ -5,6 +5,7 @@
>>  
>>  #include <sys/types.h>
>>  #include <ctype.h>
>> +#include <errno.h>
>>  #include <stdlib.h>
>>  #include <string.h>
>>  #include <regex.h>
>> @@ -711,6 +712,21 @@ bool sym_string_valid(struct symbol *sym, const char *str)
>>  	}
>>  }
>>  
>> +bool sym_string_check_bounds(struct symbol *sym, const char *str)
>> +{
>> +	errno = 0;
>> +
>> +	if (sym->type == S_INT)
>> +		strtoll(str, NULL, 10);
>> +	else if (sym->type == S_HEX)
>> +		strtoull(str, NULL, 16);
>> +	else
>> +		/* string */
>> +		return true;
>> +
>> +	return errno != ERANGE;
>> +}
>> +
>>  bool sym_string_within_range(struct symbol *sym, const char *str)
>>  {
>>  	struct property *prop;
>> @@ -722,6 +738,8 @@ bool sym_string_within_range(struct symbol *sym, const char *str)
>>  	case S_INT:
>>  		if (!sym_string_valid(sym, str))
>>  			return false;
>> +		if (!sym_string_check_bounds(sym, str))
>> +			return false;
>>  		prop = sym_get_range_prop(sym);
>>  		if (!prop)
>>  			return true;
>> @@ -731,6 +749,8 @@ bool sym_string_within_range(struct symbol *sym, const char *str)
>>  	case S_HEX:
>>  		if (!sym_string_valid(sym, str))
>>  			return false;
>> +		if (!sym_string_check_bounds(sym, str))
>> +			return false;
>>  		prop = sym_get_range_prop(sym);
>>  		if (!prop)
>>  			return true;
> 
> Sashiko has a comment that seems to be relevant here unless I
> misunderstand what it is complaining about:
> 
> https://sashiko.dev/#/patchset/64934
> 
> Otherwise, I like the direction here.
> 

Thanks, yeah it seems Sashiko found yet another instance where the
numeric bounds checks could be improved. Including this in v2.

- Julian Braha