NFC: pn533: don't send USB data off of the stack

Quoted 31 lines · Greg Kroah-Hartman

Quoted 24 lines · Johan Hovold

Quoted 15 lines · Greg Kroah-Hartman

It's amazing that this driver ever worked, but now that x86 doesn't allow USB data to be sent off of the stack, it really does not work at all. Fix this up by properly allocating the data for the small "commands" that get sent to the device off of the stack.

We do this for one command by having a whole urb just for ack messages, as they can be submitted in interrupt context, so we can not use usb_bulk_msg(). But the poweron command can sleep (and does), so use usb_bulk_msg() for that transfer.

Reported-by Carlos Manuel Santos <[email protected]>

Cc Samuel Ortiz <[email protected]>

Cc Stephen Hemminger <[email protected]>

Cc stable <[email protected]>

Signed-off-by Greg Kroah-Hartman <[email protected]>

Quoted 7 lines

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v4: don't use urb transfer buffer flags as the memory is tied to the urb
(thanks to Johan) Now we have a new static urb, and we use usb_bulk_msg() for the other message.
v3: actually use the correct buffer (thanks to Arend van Spriel)
use kmemdup (thanks to Johannes Berg and Julia Lawall)
v2: set the urb flags correctly

Quoted 3 lines

Your changes look correct now so feel free to add:

Reviewed-by Johan Hovold <[email protected]>

Thanks for the review.

Quoted 8 lines

Quoted 4 lines

It seems we could end up returning an errno from probe with active urbs (if pn533_finalize_setup() fails) in which case the ack buffer would leak. But freeing the urbs while active would then be the bigger problem, and that wasn't introduced by this patch.

Yeah, this whole thing is a mess and I really don't want to do much more to the driver without having the hardware to test with it. So I'll just leave it as-is for now :)

Hi Greg.

I have a pn533 USB stick, a trf7970-based board, and some nfc tags so I can help you test as long as you don't mind multi-day turn-around times. Alternatively, I can set something up and give you remote access, if you prefer that.

Let me know.