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

Hans Zhang
2025-01-06T15:32:58Z

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