On 06/01/2016 04:55 PM, Rajesh Bhagat wrote:
>
>
>> -----Original Message-----
>> From: Marek Vasut [mailto:[email protected]]
>> Sent: Wednesday, June 01, 2016 6:51 PM
>> To: Rajesh Bhagat <[email protected]>; [email protected]
>> Cc: york sun <[email protected]>; Sriram Dash <[email protected]>
>> Subject: Re: [PATCH] drivers: usb: fsl: Fix NULL terminating issue for usb
>> controller
>> name string
>>
>> On 06/01/2016 01:17 PM, Rajesh Bhagat wrote:
>>> Fixes NULL terminating issue for usb controller name string and
>>> performs code cleanup for intializing variables current_usb_controller
>>> and usb_phy.
>>>
>>> Signed-off-by: Rajesh Bhagat <[email protected]>
>>> ---
>>> drivers/usb/host/ehci-fsl.c | 10 ++++------
>>> 1 files changed, 4 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/drivers/usb/host/ehci-fsl.c b/drivers/usb/host/ehci-fsl.c
>>> index a43d37d..a806993 100644
>>> --- a/drivers/usb/host/ehci-fsl.c
>>> +++ b/drivers/usb/host/ehci-fsl.c
>>> @@ -49,11 +49,9 @@ int ehci_hcd_init(int index, enum usb_init_type init,
>>> struct usb_ehci *ehci = NULL;
>>> const char *phy_type = NULL;
>>> size_t len;
>>> - char current_usb_controller[5];
>>> + char current_usb_controller[5] = {0};
>>> #ifdef CONFIG_SYS_FSL_USB_INTERNAL_UTMI_PHY
>>> - char usb_phy[5];
>>> -
>>> - usb_phy[0] = '\0';
>>> + char usb_phy[5] = {0};
>>> #endif
>>> if (has_erratum_a007075()) {
>>> /*
>>> @@ -64,8 +62,8 @@ int ehci_hcd_init(int index, enum usb_init_type init,
>>> */
>>> mdelay(5);
>>> }
>>> - memset(current_usb_controller, '\0', 5);
>>> - snprintf(current_usb_controller, 4, "usb%d", index+1);
>>> + snprintf(current_usb_controller, sizeof(current_usb_controller),
>>> + "usb%d", index+1);
>>
>> What is the actual problem here ? snprintf() will add the \0 at the end of
>> the string, so
>> I don't see any "null terminating issue" in the code.
>> I can understand using the sizeof() in the snprintf(), which is valid, but
>> that's all.
>>
>
> Hello Marek,
>
> It is surprising for me too, but same can be verified even on x86 machine
> using below test
> program, Can it be compiler optimization of memset?
The man snprintf explains that:
int snprintf(char *str, size_t size, const char *format, ...);
The functions snprintf() and vsnprintf() write at most size bytes
(including the terminating null byte ('\0')) to str.
> Output #1 : current_usb_controller usb
> Output #2 : current_usb_controller usb1 (Expected Output)
>
> int main()
> {
> int index = 0;
> #if 1
> char current_usb_controller[5];
> memset(current_usb_controller, '\0', 5);
> snprintf(current_usb_controller, 4, "usb%d", index+1);
> #else
> char current_usb_controller[5] = {0};
> snprintf(current_usb_controller, sizeof(current_usb_controller),
> "usb%d", index+1);
> #endif
>
> printf("current_usb_controller %s\n", current_usb_controller);
> return 0;
> }
>
> Best Regards,
> Rajesh Bhagat
>
>>> switch (index) {
>>> case 0:
>>>
>>
>>
>> --
>> Best regards,
>> Marek Vasut
--
Best regards,
Marek Vasut
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