Re: [v8] misc: pci_endpoint_test: Fix overflow of bar_size

[Hans Zhang]

On 2025/1/6 19:49, Niklas Cassel wrote:
> Doing a:
> $ git grep -A 10 "IS_ENABLED(CONFIG_PHYS_ADDR_T_64BIT"
> does not show very many hits, which suggests that this is not the proper
> way to solve this.
>
> I don't know the proper solution to this. How is resource_size_t handled
> in other PCI driver when being built on with 32-bit PHYS_ADDR_T ?
>
> Can't you just cast the resource_size_t to u64 before doing the division?

Hi Niklas,

Modify as follows, if you have no opinion, I will fix the next version.

> > ---
> >   drivers/misc/pci_endpoint_test.c | 12 +++++++++---
> >   1 file changed, 9 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
> > index 3aaaf47fa4ee..50d4616119af 100644
> > --- a/drivers/misc/pci_endpoint_test.c
> > +++ b/drivers/misc/pci_endpoint_test.c
> > @@ -280,10 +280,11 @@ static int pci_endpoint_test_bar_memcmp(struct pci_endpoint_test *test,
> >   static bool pci_endpoint_test_bar(struct pci_endpoint_test *test,
> >   				  enum pci_barno barno)
> >   {
> > -	int j, bar_size, buf_size, iters, remain;
> >   	void *write_buf __free(kfree) = NULL;
> >   	void *read_buf __free(kfree) = NULL;
> >   	struct pci_dev *pdev = test->pdev;
> > +	int j, buf_size, iters, remain;
> > +	resource_size_t bar_size;

Fix resource_size_t to u64 bar_size.
u64 bar_size;

> >   
> >   	if (!test->bar[barno])
> >   		return false;
> > @@ -307,13 +308,18 @@ static bool pci_endpoint_test_bar(struct pci_endpoint_test *test,
> >   	if (!read_buf)
> >   		return false;
> >   
> > -	iters = bar_size / buf_size;
> > +	if (IS_ENABLED(CONFIG_PHYS_ADDR_T_64BIT)) {
> > +		remain = do_div(bar_size, buf_size);
> > +		iters = bar_size;
> > +	} else {
> > +		iters = bar_size / buf_size;
> > +		remain = bar_size % buf_size;
> > +	}

Removed IS_ENABLED(CONFIG_PHYS_ADDR_T_64BIT), Execute the following code.

remain = do_div(bar_size, buf_size);
iters = bar_size;

> >   	for (j = 0; j < iters; j++)
> >   		if (pci_endpoint_test_bar_memcmp(test, barno, buf_size * j,
> >   						 write_buf, read_buf, buf_size))
> >   			return false;
> >   
> > -	remain = bar_size % buf_size;
> >   	if (remain)
> >   		if (pci_endpoint_test_bar_memcmp(test, barno, buf_size * iters,
> >   						 write_buf, read_buf, remain))
> >
> > base-commit: ccb98ccef0e543c2bd4ef1a72270461957f3d8d0
> > --
> > 2.25.1

Best regards
Hans