Re: [PATCH v2] sysctl: move the extra1/2 boundary check of u8 to sysctl_check_table_array

[Wen Yang]

On 2024/3/29 00:53, Joel Granados wrote:
> On Sat, Mar 02, 2024 at 11:27:45PM +0800, wenyang.linux@xxxxxxxxxxx wrote:
> > From: Wen Yang <wenyang.linux@xxxxxxxxxxx>
>
> <--- snip --->
>
> > diff --git a/kernel/sysctl-test.c b/kernel/sysctl-test.c
> > index 6ef887c19c48..84e759a8328f 100644
> > --- a/kernel/sysctl-test.c
> > +++ b/kernel/sysctl-test.c
> > @@ -367,6 +367,35 @@ static void sysctl_test_api_dointvec_write_single_greater_int_max(
> >   	KUNIT_EXPECT_EQ(test, 0, *((int *)table.data));
> >   }
> >   
> > +/*
> > + * Test that registering an invalid extra value is not allowed.
> > + */
> > +static void sysctl_test_register_sysctl_sz_invalid_extra_value(
> > +		struct kunit *test)
> > +{
> > +	unsigned char data = 0;
> > +	struct ctl_table table[] = {
> I'm pretty sure that this is going to clash with the constification that
> Thomas is working on. Please re-work this patch knowing that these
> ctl_tables are going to have to change to const at some point.
>
> > +		{
> > +			.procname	= "foo",
> > +			.data		= &data,
> > +			.maxlen		= sizeof(u8),
> > +			.mode		= 0644,
> > +			.proc_handler	= proc_dou8vec_minmax,
> > +			.extra1		= SYSCTL_ZERO,
> > +			.extra2		= SYSCTL_ONE_THOUSAND,
> > +		},
> > +		{}
> Don't use the sentinel here. We are removing them and all new sysctl
> tables (even the test ones) should be created without them
>
> > +	};
> > +	unsigned int size = ARRAY_SIZE(table);
> You do not need size here. When you use register_sysctl, the size will
> be automatically calculated for you.
>
> > +
> > +	KUNIT_EXPECT_NULL(test, register_sysctl_sz("foo", table, size));
> > +	table[0].extra1 = SYSCTL_ONE_THOUSAND;
> > +	KUNIT_EXPECT_NULL(test, register_sysctl_sz("foo", table, size));
> > +	table[0].extra1 = SYSCTL_ONE_HUNDRED;
> > +	table[0].extra2 = SYSCTL_TWO_HUNDRED;
> > +	KUNIT_EXPECT_NOT_NULL(test, register_sysctl_sz("foo", table, size));
> Replace all these by register_sysctl please.
Thanks for your review comments w.r.t [PATCH v2], which will be complied 
by in next patch version [PATCH v3].

--
Best wishes,
Wen

> > +}
> > +
> >   static struct kunit_case sysctl_test_cases[] = {
> >   	KUNIT_CASE(sysctl_test_api_dointvec_null_tbl_data),
> >   	KUNIT_CASE(sysctl_test_api_dointvec_table_maxlen_unset),
> > @@ -378,6 +407,7 @@ static struct kunit_case sysctl_test_cases[] = {
> >   	KUNIT_CASE(sysctl_test_dointvec_write_happy_single_negative),
> >   	KUNIT_CASE(sysctl_test_api_dointvec_write_single_less_int_min),
> >   	KUNIT_CASE(sysctl_test_api_dointvec_write_single_greater_int_max),
> > +	KUNIT_CASE(sysctl_test_register_sysctl_sz_invalid_extra_value),
> >   	{}
> >   };
> >   
> > diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> > index f67b39d3d6e5..28888744626a 100644
> > --- a/kernel/sysctl.c
> > +++ b/kernel/sysctl.c
> > @@ -977,16 +977,10 @@ int proc_dou8vec_minmax(struct ctl_table *table, int write,
> >   	if (table->maxlen != sizeof(u8))
> >   		return -EINVAL;
> >   
> > -	if (table->extra1) {
> > -		min = *(unsigned int *) table->extra1;
> > -		if (min > 255U)
> > -			return -EINVAL;
> > -	}
> > -	if (table->extra2) {
> > -		max = *(unsigned int *) table->extra2;
> > -		if (max > 255U)
> > -			return -EINVAL;
> > -	}
> > +	if (table->extra1)
> > +		min = *(unsigned char *) table->extra1;
> > +	if (table->extra2)
> > +		max = *(unsigned char *) table->extra2;
> >   
> >   	tmp = *table;
> >   
> > --
> > 2.25.1