Re: [PATCH] usb: core: buffer: avoid NULL pointer dereferrence

From	Felipe Balbi <felipe.balbi@linux.intel.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] usb: core: buffer: avoid NULL pointer dereferrence
Date	2016-04-11 07:20 +0200
Message-ID	<rmCqt-vD-1@gated-at.bofh.it> (permalink)
References	<rlAAq-1tY-29@gated-at.bofh.it> <rlFgK-4ZO-15@gated-at.bofh.it> <rmAoG-7sx-15@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

[Multipart message — attachments visible in raw view] - view raw

Hi,

chunfeng yun <chunfeng.yun@mediatek.com> writes:
> On Fri, 2016-04-08 at 07:07 -0700, Greg Kroah-Hartman wrote:
>> On Fri, Apr 08, 2016 at 05:08:03PM +0800, Chunfeng Yun wrote:
>> > NULL pointer dereferrence will happen when class driver
>> > wants to allocate zero length buffer and pool_max[0]
>> > can't be used, so skip reserved pool in this case.
>> 
>> Why would a driver want to allocate a 0 length buffer?  What driver does
>> this?
> It's misc/usbtest.c

that'll do what you ask it to do with the userspace tool testusb. Are
you trying to pass a size of 0 ?

>> Shouldn't we fix that issue instead?
> I don't know which way is better, but it seems simple to fix it up in
> buffer.c 

I think we should, really, avoid a 0-length allocation, but passing a
size of 0 to testusb isn't very good either ;-) How are you calling
testusb ?

-- 
balbi

Thread

[PATCH] usb: core: buffer: avoid NULL pointer dereferrence Chunfeng Yun <chunfeng.yun@mediatek.com> - 2016-04-08 11:10 +0200
  Re: [PATCH] usb: core: buffer: avoid NULL pointer dereferrence Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-08 16:10 +0200
    Re: [PATCH] usb: core: buffer: avoid NULL pointer dereferrence Alan Stern <stern@rowland.harvard.edu> - 2016-04-08 17:30 +0200
    Re: [PATCH] usb: core: buffer: avoid NULL pointer dereferrence chunfeng yun <chunfeng.yun@mediatek.com> - 2016-04-11 05:10 +0200
      Re: [PATCH] usb: core: buffer: avoid NULL pointer dereferrence Felipe Balbi <felipe.balbi@linux.intel.com> - 2016-04-11 07:20 +0200
        Re: [PATCH] usb: core: buffer: avoid NULL pointer dereferrence chunfeng yun <chunfeng.yun@mediatek.com> - 2016-04-11 09:20 +0200
          Re: [PATCH] usb: core: buffer: avoid NULL pointer dereferrence Felipe Balbi <felipe.balbi@linux.intel.com> - 2016-04-11 10:30 +0200
          Re: [PATCH] usb: core: buffer: avoid NULL pointer dereferrence Alan Stern <stern@rowland.harvard.edu> - 2016-04-11 16:50 +0200

csiph-web