On Thu, Nov 11, 2010 at 13:34 -0800, David Rientjes wrote:
> On Fri, 12 Nov 2010, Vasiliy Kulikov wrote:
> > OK, if the main reason here is return value type, then the correct
> > handling should be:
> >
> > /* Reject out-of-range values early. Large positive sizes are
> > used for unknown buffer sizes. */
> > - if (WARN_ON_ONCE((int) size < 0))
> > + if (WARN_ON_ONCE(size > INT_MAX)
> > return 0;
> >
> > This should catch all underflows and too big integers.
> >
>
> That is equivalent since size_t is always unsigned;
Not equivalent:
void test_size(size_t size)
{
char buffer[128];
sprintf(buffer, "size %lx is BAD", size);
snprintf(buffer, size, "size %lx is OK", size);
pr_info("%s\n", buffer);
if (size > INT_MAX)
pr_info("%lx is catched by (size) > INT_MAX", size);
}
static int init(void) {
test_size(0x7FFFFFFF);
test_size(0x80000000);
test_size(0x80000001);
test_size(0xFFFFFFFF);
test_size(0x100000000);
test_size(0x100000001);
test_size(0x17fffffff);
test_size(0x180000000);
test_size(0x180000001);
return 0;
}
Output on x86_64:
[12486.542047] size 7fffffff is OK
[12486.542051] size 80000000 is BAD
[12486.542053] 80000000 is catched by (size) > INT_MAX
[12486.542055] size 80000001 is BAD
[12486.542057] 80000001 is catched by (size) > INT_MAX
[12486.542059] size ffffffff is BAD
[12486.542061] ffffffff is catched by (size) > INT_MAX
[12486.542063] size 100000000 is OK
[12486.542065] 100000000 is catched by (size) > INT_MAX
[12486.542067] size 100000001 is OK
[12486.542069] 100000001 is catched by (size) > INT_MAX
[12486.542071] size 17fffffff is OK
[12486.542073] 17fffffff is catched by (size) > INT_MAX
[12486.542075] size 180000000 is BAD
[12486.542077] 180000000 is catched by (size) > INT_MAX
[12486.542079] size 180000001 is BAD
[12486.542081] 180000001 is catched by (size) > INT_MAX
--
Vasiliy
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