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Message-ID: <ce76c90b-3431-9342-8b75-882d582c6366@kernel.org>
Date: Thu, 24 Oct 2019 16:52:52 -0600
From: shuah <shuah@...nel.org>
To: Dan Carpenter <dan.carpenter@...cle.com>,
Suwan Kim <suwan.kim027@...il.com>
Cc: kbuild@...ts.01.org, kbuild-all@...ts.01.org,
linux-kernel@...r.kernel.org,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-usb@...r.kernel.org, shuah <shuah@...nel.org>
Subject: Re: drivers/usb/usbip/stub_rx.c:505 stub_recv_cmd_submit() error:
uninitialized symbol 'nents'.
On 10/24/19 1:45 PM, Dan Carpenter wrote:
> On Wed, Oct 23, 2019 at 04:11:20PM +0900, Suwan Kim wrote:
>> On Tue, Oct 22, 2019 at 12:28:39PM +0300, Dan Carpenter wrote:
>>> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>>> head: 7d194c2100ad2a6dded545887d02754948ca5241
>>> commit: ea44d190764b4422af4d1c29eaeb9e69e353b406 usbip: Implement SG support to vhci-hcd and stub driver
>>> date: 7 weeks ago
>>>
>>> If you fix the issue, kindly add following tag
>>> Reported-by: kbuild test robot <lkp@...el.com>
>>> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
>>>
>>> New smatch warnings:
>>> drivers/usb/usbip/stub_rx.c:505 stub_recv_cmd_submit() error: uninitialized symbol 'nents'.
>>>
>>> Old smatch warnings:
>>> drivers/usb/usbip/stub_rx.c:450 stub_recv_xbuff() error: uninitialized symbol 'ret'.
>>>
>>> # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ea44d190764b4422af4d1c29eaeb9e69e353b406
>>> git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>>> git remote update linus
>>> git checkout ea44d190764b4422af4d1c29eaeb9e69e353b406
>>> vim +/nents +505 drivers/usb/usbip/stub_rx.c
>>>
>>> 4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09 453 static void stub_recv_cmd_submit(struct stub_device *sdev,
>>> 4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09 454 struct usbip_header *pdu)
>>> 4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09 455 {
>>> 4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09 456 struct stub_priv *priv;
>>> 4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09 457 struct usbip_device *ud = &sdev->ud;
>>> 2d8f4595d1f275 drivers/staging/usbip/stub_rx.c Max Vozeler 2011-01-12 458 struct usb_device *udev = sdev->udev;
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 459 struct scatterlist *sgl = NULL, *sg;
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 460 void *buffer = NULL;
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 461 unsigned long long buf_len;
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 462 int nents;
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 463 int num_urbs = 1;
>>> c6688ef9f29762 drivers/usb/usbip/stub_rx.c Shuah Khan 2017-12-07 464 int pipe = get_pipe(sdev, pdu);
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 465 int use_sg = pdu->u.cmd_submit.transfer_flags & URB_DMA_MAP_SG;
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 466 int support_sg = 1;
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 467 int np = 0;
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 468 int ret, i;
>>> 4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09 469
>>> 635f545a7e8be7 drivers/usb/usbip/stub_rx.c Shuah Khan 2017-12-07 470 if (pipe == -1)
>>> 635f545a7e8be7 drivers/usb/usbip/stub_rx.c Shuah Khan 2017-12-07 471 return;
>>> 4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09 472
>>> 4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09 473 priv = stub_priv_alloc(sdev, pdu);
>>> 4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09 474 if (!priv)
>>> 4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09 475 return;
>>> 4d7b5c7f8ad49b drivers/staging/usbip/stub_rx.c Takahiro Hirofuchi 2008-07-09 476
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 477 buf_len = (unsigned long long)pdu->u.cmd_submit.transfer_buffer_length;
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 478
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 479 /* allocate urb transfer buffer, if needed */
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 480 if (buf_len) {
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 481 if (use_sg) {
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 482 sgl = sgl_alloc(buf_len, GFP_KERNEL, &nents);
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 483 if (!sgl)
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 484 goto err_malloc;
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 485 } else {
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 486 buffer = kzalloc(buf_len, GFP_KERNEL);
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 487 if (!buffer)
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 488 goto err_malloc;
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 489 }
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 490 }
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 491
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 492 /* Check if the server's HCD supports SG */
>>> ea44d190764b44 drivers/usb/usbip/stub_rx.c Suwan Kim 2019-08-28 493 if (use_sg && !udev->bus->sg_tablesize) {
>>>
>>> Smatch thinks "use_sg" can be true when "buf_len" is zero. It's hard
>>> to tell if Smatch is right or wrong without more context...
>>
>> This is a bit strange. The meaning of "use_sg" is that client will
>> use scatter-gather and client's urb->num_sgs is not zero. And buffer
>> length should not be zero.
>>
>> usb_sg and buf_len are both client-dependent variables, so I think
>> if they have wrong value in the server side, the client must have
>> sent use_sg and buf_len with incorrect values.
>>
>> Did this error occur when compiling?
>
> Smatch is doing static analysis, yes.
>
>> If then, Did Smatch also consider vhci tx side?
>
> I'm not really sure... I can't reproduce the warning because on my
> system Smatch doesn't parse usbip_recv() correctly so it ends up
> silencing that warning. :/
>
Hi Suwan,
This is a problem that needs fixing. nents
/* allocate urb transfer buffer, if needed */
if (buf_len) {
if (use_sg) {
sgl = sgl_alloc(buf_len, GFP_KERNEL, &nents);
nents gets initialized here by sgl_alloc()
if (!sgl)
goto err_malloc;
} else {
buffer = kzalloc(buf_len, GFP_KERNEL);
if (!buffer)
goto err_malloc;
}
}
/* Check if the server's HCD supports SG */
if (use_sg && !udev->bus->sg_tablesize) {
/*
* If the server's HCD doesn't support SG, break a
single SG
* request into several URBs and map each SG list entry to
* corresponding URB buffer. The previously allocated SG
* list is stored in priv->sgl (If the server's HCD
support SG,
* SG list is stored only in urb->sg) and it is used as an
* indicator that the server split single SG request into
* several URBs. Later, priv->sgl is used by
stub_complete() and
* stub_send_ret_submit() to reassemble the divied URBs.
*/
support_sg = 0;
num_urbs = nents;
I think nents will be valid here. Is there need for this additional
check here? You can fold this into the previous use_sg check, right
after the sg_alloc() success, I would think.
priv->completed_urbs = 0;
pdu->u.cmd_submit.transfer_flags &= ~URB_DMA_MAP_SG;
}
thanks,
-- Shuah
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