* usb: storage: suspicious code
@ 2017-02-15 5:06 Gustavo A. R. Silva
2017-02-15 7:01 ` [usb-storage] " Oliver Neukum
0 siblings, 1 reply; 6+ messages in thread
From: Gustavo A. R. Silva @ 2017-02-15 5:06 UTC (permalink / raw)
To: stern, gregkh
Cc: linux-usb, usb-storage, linux-kernel, Peter Senna Tschudi,
Gustavo A. R. Silva
Hello,
I ran into the following piece of code at drivers/usb/storage/jumpshot.c:305 (linux-next), and it seems a little bit suspicious:
// read the result. apparently the bulk write can complete
// before the jumpshot drive is finished writing. so we loop
// here until we get a good return code
waitcount = 0;
do {
result = jumpshot_get_status(us);
if (result != USB_STOR_TRANSPORT_GOOD) {
// I have not experimented to find the smallest value.
//
msleep(50);
}
} while ((result != USB_STOR_TRANSPORT_GOOD) && (waitcount < 10));
if (result != USB_STOR_TRANSPORT_GOOD)
usb_stor_dbg(us, "Gah! Waitcount = 10. Bad write!?\n");
Variable 'waitcount' is never updated inside the do-while loop. So, either it isn't needed at all or line 316 should be modified (++waitcount < 10)
In case 'waitcount' isn't needed, lines 318 and 319 should be removed.
Can someone help me to clarify this so I can write a patch to fix this code?
Thank you
--
Gustavo A. R. Silva
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [usb-storage] usb: storage: suspicious code
2017-02-15 5:06 usb: storage: suspicious code Gustavo A. R. Silva
@ 2017-02-15 7:01 ` Oliver Neukum
2017-02-15 7:14 ` Gustavo A. R. Silva
0 siblings, 1 reply; 6+ messages in thread
From: Oliver Neukum @ 2017-02-15 7:01 UTC (permalink / raw)
To: Gustavo A. R. Silva, stern, gregkh
Cc: linux-usb, usb-storage, linux-kernel, Peter Senna Tschudi
Am Dienstag, den 14.02.2017, 23:06 -0600 schrieb Gustavo A. R. Silva:
Hi,
> waitcount = 0;
> do {
> result = jumpshot_get_status(us);
> if (result != USB_STOR_TRANSPORT_GOOD) {
> // I have not experimented to find the smallest
> value.
> //
> msleep(50);
> }
> } while ((result != USB_STOR_TRANSPORT_GOOD) && (waitcount <
> 10));
>
> if (result != USB_STOR_TRANSPORT_GOOD)
> usb_stor_dbg(us, "Gah! Waitcount = 10. Bad
> write!?\n");
>
> Variable 'waitcount' is never updated inside the do-while loop. So,
> either it isn't needed at all or line 316 should be modified
> (++waitcount < 10)
you are correct. Waitcount needs to be incremented.
HTH
Oliver
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [usb-storage] usb: storage: suspicious code
2017-02-15 7:01 ` [usb-storage] " Oliver Neukum
@ 2017-02-15 7:14 ` Gustavo A. R. Silva
2017-02-15 7:39 ` [PATCH] usb: storage: add missing pre-increment to variable Gustavo A. R. Silva
0 siblings, 1 reply; 6+ messages in thread
From: Gustavo A. R. Silva @ 2017-02-15 7:14 UTC (permalink / raw)
To: Oliver Neukum
Cc: stern, gregkh, linux-usb, usb-storage, linux-kernel,
Peter Senna Tschudi
Hi Oliver,
Quoting Oliver Neukum <oneukum@suse.com>:
> Am Dienstag, den 14.02.2017, 23:06 -0600 schrieb Gustavo A. R. Silva:
>
> Hi,
>
>> waitcount = 0;
>> do {
>> result = jumpshot_get_status(us);
>> if (result != USB_STOR_TRANSPORT_GOOD) {
>> // I have not experimented to find the smallest
>> value.
>> //
>> msleep(50);
>> }
>> } while ((result != USB_STOR_TRANSPORT_GOOD) && (waitcount <
>> 10));
>>
>> if (result != USB_STOR_TRANSPORT_GOOD)
>> usb_stor_dbg(us, "Gah! Waitcount = 10. Bad
>> write!?\n");
>>
>> Variable 'waitcount' is never updated inside the do-while loop. So,
>> either it isn't needed at all or line 316 should be modified
>> (++waitcount < 10)
>
> you are correct. Waitcount needs to be incremented.
>
Thanks for clarifying, I'll send a patch shortly.
--
Gustavo A. R. Silva
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH] usb: storage: add missing pre-increment to variable
2017-02-15 7:14 ` Gustavo A. R. Silva
@ 2017-02-15 7:39 ` Gustavo A. R. Silva
2017-02-15 15:26 ` [usb-storage] " Alan Stern
0 siblings, 1 reply; 6+ messages in thread
From: Gustavo A. R. Silva @ 2017-02-15 7:39 UTC (permalink / raw)
To: oneukum, stern, gregkh
Cc: linux-usb, usb-storage, linux-kernel, Peter Senna Tschudin,
Gustavo A. R. Silva
Add missing pre-increment to 'waitcount' variable used in do-while loop.
Addresses-Coverity-ID: 1011631
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
---
drivers/usb/storage/jumpshot.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/usb/storage/jumpshot.c b/drivers/usb/storage/jumpshot.c
index 011e527..a26c4bb 100644
--- a/drivers/usb/storage/jumpshot.c
+++ b/drivers/usb/storage/jumpshot.c
@@ -313,7 +313,7 @@ static int jumpshot_write_data(struct us_data *us,
//
msleep(50);
}
- } while ((result != USB_STOR_TRANSPORT_GOOD) && (waitcount < 10));
+ } while ((result != USB_STOR_TRANSPORT_GOOD) && (++waitcount < 10));
if (result != USB_STOR_TRANSPORT_GOOD)
usb_stor_dbg(us, "Gah! Waitcount = 10. Bad write!?\n");
--
2.5.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [usb-storage] [PATCH] usb: storage: add missing pre-increment to variable
2017-02-15 7:39 ` [PATCH] usb: storage: add missing pre-increment to variable Gustavo A. R. Silva
@ 2017-02-15 15:26 ` Alan Stern
2017-02-20 23:07 ` Gustavo A. R. Silva
0 siblings, 1 reply; 6+ messages in thread
From: Alan Stern @ 2017-02-15 15:26 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: oneukum, gregkh, linux-usb, usb-storage, linux-kernel,
Peter Senna Tschudin
On Wed, 15 Feb 2017, Gustavo A. R. Silva wrote:
> Add missing pre-increment to 'waitcount' variable used in do-while loop.
>
> Addresses-Coverity-ID: 1011631
> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
> ---
> drivers/usb/storage/jumpshot.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/usb/storage/jumpshot.c b/drivers/usb/storage/jumpshot.c
> index 011e527..a26c4bb 100644
> --- a/drivers/usb/storage/jumpshot.c
> +++ b/drivers/usb/storage/jumpshot.c
> @@ -313,7 +313,7 @@ static int jumpshot_write_data(struct us_data *us,
> //
> msleep(50);
> }
> - } while ((result != USB_STOR_TRANSPORT_GOOD) && (waitcount < 10));
> + } while ((result != USB_STOR_TRANSPORT_GOOD) && (++waitcount < 10));
>
> if (result != USB_STOR_TRANSPORT_GOOD)
> usb_stor_dbg(us, "Gah! Waitcount = 10. Bad write!?\n");
>
This has already been reported and fixed. See
http://marc.info/?l=linux-usb&m=148604164024557&w=2
Alan Stern
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [usb-storage] [PATCH] usb: storage: add missing pre-increment to variable
2017-02-15 15:26 ` [usb-storage] " Alan Stern
@ 2017-02-20 23:07 ` Gustavo A. R. Silva
0 siblings, 0 replies; 6+ messages in thread
From: Gustavo A. R. Silva @ 2017-02-20 23:07 UTC (permalink / raw)
To: Alan Stern
Cc: oneukum, gregkh, linux-usb, usb-storage, linux-kernel,
Peter Senna Tschudin
Hi Alan,
Quoting Alan Stern <stern@rowland.harvard.edu>:
> On Wed, 15 Feb 2017, Gustavo A. R. Silva wrote:
>
>> Add missing pre-increment to 'waitcount' variable used in do-while loop.
>>
>> Addresses-Coverity-ID: 1011631
>> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
>> ---
>> drivers/usb/storage/jumpshot.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/storage/jumpshot.c b/drivers/usb/storage/jumpshot.c
>> index 011e527..a26c4bb 100644
>> --- a/drivers/usb/storage/jumpshot.c
>> +++ b/drivers/usb/storage/jumpshot.c
>> @@ -313,7 +313,7 @@ static int jumpshot_write_data(struct us_data *us,
>> //
>> msleep(50);
>> }
>> - } while ((result != USB_STOR_TRANSPORT_GOOD) && (waitcount < 10));
>> + } while ((result != USB_STOR_TRANSPORT_GOOD) && (++waitcount < 10));
>>
>> if (result != USB_STOR_TRANSPORT_GOOD)
>> usb_stor_dbg(us, "Gah! Waitcount = 10. Bad write!?\n");
>>
>
> This has already been reported and fixed. See
>
> http://marc.info/?l=linux-usb&m=148604164024557&w=2
>
Awesome. Thanks for the info.
--
Gustavo A. R. Silva
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2017-02-20 23:33 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2017-02-15 5:06 usb: storage: suspicious code Gustavo A. R. Silva
2017-02-15 7:01 ` [usb-storage] " Oliver Neukum
2017-02-15 7:14 ` Gustavo A. R. Silva
2017-02-15 7:39 ` [PATCH] usb: storage: add missing pre-increment to variable Gustavo A. R. Silva
2017-02-15 15:26 ` [usb-storage] " Alan Stern
2017-02-20 23:07 ` Gustavo A. R. Silva
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