linux-kernel - Re: [v11 2/2] misc: pci_endpoint_test: Fix overflow of bar

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Message-ID: <11b41380-9ab1-4628-8e1b-2a71a7b92a0c@nvidia.com>
Date: Wed, 22 Jan 2025 06:03:04 +0000
From: Jon Hunter <jonathanh@...dia.com>
To: Niklas Cassel <cassel@...nel.org>, Hans Zhang <18255117159@....com>,
 manivannan.sadhasivam@...aro.org
Cc: kw@...ux.com, kishon@...nel.org, arnd@...db.de,
 gregkh@...uxfoundation.org, linux-pci@...r.kernel.org,
 linux-kernel@...r.kernel.org, rockswang7@...il.com,
 "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: Re: [v11 2/2] misc: pci_endpoint_test: Fix overflow of bar_size


On 21/01/2025 20:31, Niklas Cassel wrote:
> 
> 
> On 21 January 2025 18:46:43 CET, Jon Hunter <jonathanh@...dia.com> wrote:
>> Hi Hans,
>>
>> On 09/01/2025 09:45, Hans Zhang wrote:
>>> With 8GB BAR2, running pcitest -b 2 fails with "TEST FAILED".
>>>
>>> The return value of the `pci_resource_len` interface is not an integer.
>>> Using `pcitest` with an 8GB BAR2, the bar_size of integer type will
>>> overflow.
>>>
>>> Change the data type of bar_size from integer to resource_size_t, to fix
>>> the above issue.
>>>
>>> Signed-off-by: Hans Zhang <18255117159@....com>
>>> Suggested-by: Niklas Cassel <cassel@...nel.org>
>>> Reviewed-by: Niklas Cassel <cassel@...nel.org>
>>> ---
>>> Changes since v10:
>>> https://lore.kernel.org/linux-pci/20250108080951.1700230-3-18255117159@163.com/
>>>
>>> - Replace do_div with the div_u64 API.
>>>
>>> Changes since v8-v9:
>>> https://lore.kernel.org/linux-pci/20250104151652.1652181-1-18255117159@163.com/
>>>
>>> - Split the patch.
>>>
>>> Changes since v4-v7:
>>> https://lore.kernel.org/linux-pci/20250102120222.1403906-1-18255117159@163.com/
>>>
>>> - Fix 32-bit OS warnings and errors.
>>> - Fix undefined reference to `__udivmoddi4`
>>>
>>> Changes since v3:
>>> https://lore.kernel.org/linux-pci/20241221141009.27317-1-18255117159@163.com/
>>>
>>> - The patch subject were modified.
>>>
>>> Changes since v2:
>>> https://lore.kernel.org/linux-pci/20241220075253.16791-1-18255117159@163.com/
>>>
>>> - Fix "changes" part goes below the --- line
>>> - The patch commit message were modified.
>>>
>>> Changes since v1:
>>> https://lore.kernel.org/linux-pci/20241217121220.19676-1-18255117159@163.com/
>>>
>>> - The patch subject and commit message were modified.
>>> ---
>>>    drivers/misc/pci_endpoint_test.c | 5 +++--
>>>    1 file changed, 3 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
>>> index f78c7540c52c..0f6291801078 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;
>>> +	int j, buf_size, iters;
>>>    	void *write_buf __free(kfree) = NULL;
>>>    	void *read_buf __free(kfree) = NULL;
>>>    	struct pci_dev *pdev = test->pdev;
>>> +	resource_size_t bar_size;
>>>      	if (!test->bar[barno])
>>>    		return false;
>>> @@ -307,7 +308,7 @@ static bool pci_endpoint_test_bar(struct pci_endpoint_test *test,
>>>    	if (!read_buf)
>>>    		return false;
>>>    -	iters = bar_size / buf_size;
>>> +	iters = div_u64(bar_size, buf_size);
>>>    	for (j = 0; j < iters; j++)
>>>    		if (pci_endpoint_test_bar_memcmp(test, barno, buf_size * j,
>>>    						 write_buf, read_buf, buf_size))
>>
>>
>> This change breaks building the kernel with GCC v7 and I see ...
>>
>> ERROR: modpost: "__aeabi_uldivmod" [drivers/misc/pci_endpoint_test.ko] undefined!
>> ERROR: modpost: "__aeabi_ldivmod" [drivers/misc/pci_endpoint_test.ko] undefined!
>>
>> I know that this is an old GCC version, but this is a farm builder and the kernel still indicates that GCC v5.1 is still supported [0].
>>
> 
> Hmm.. div_u64() should work on gcc 5.1.
> 
> Out of curiosity, is there any difference if you add:
> 
> #include <linux/math64.h>
> to
> drivers/misc/pci_endpoint_test.c ?


I tried the above, but I am still seeing the same problem. So 
unfortunately, that did not fix it.

Cheers
Jon

-- 
nvpublic