diff mbox series

rt2x00: reset reg earlier in rt2500usb_register_read

Message ID 20210121092026.3261412-1-mudongliangabcd@gmail.com
State Superseded
Headers show
Series rt2x00: reset reg earlier in rt2500usb_register_read | expand

Commit Message

Dongliang Mu Jan. 21, 2021, 9:20 a.m. UTC 
In the function rt2500usb_register_read(_lock), reg is uninitialized
in some situation. Then KMSAN reports uninit-value at its first memory
access. To fix this issue, add one reg initialization in the function
rt2500usb_register_read and rt2500usb_register_read_lock

BUG: KMSAN: uninit-value in rt2500usb_init_eeprom rt2500usb.c:1443 [inline]
BUG: KMSAN: uninit-value in rt2500usb_probe_hw+0xb5e/0x22a0 rt2500usb.c:1757
CPU: 0 PID: 3369 Comm: kworker/0:2 Not tainted 5.3.0-rc7+ #0
Hardware name: Google Compute Engine
Workqueue: usb_hub_wq hub_event
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x191/0x1f0 lib/dump_stack.c:113
 kmsan_report+0x162/0x2d0 mm/kmsan/kmsan_report.c:109
 __msan_warning+0x75/0xe0 mm/kmsan/kmsan_instr.c:294
 rt2500usb_init_eeprom wireless/ralink/rt2x00/rt2500usb.c:1443 [inline]
 rt2500usb_probe_hw+0xb5e/0x22a0 wireless/ralink/rt2x00/rt2500usb.c:1757
 rt2x00lib_probe_dev+0xba9/0x3260 wireless/ralink/rt2x00/rt2x00dev.c:1427
 rt2x00usb_probe+0x7ae/0xf60 wireless/ralink/rt2x00/rt2x00usb.c:842
 rt2500usb_probe+0x50/0x60 wireless/ralink/rt2x00/rt2500usb.c:1966
 ......

Local variable description: ----reg.i.i@rt2500usb_probe_hw
Variable was created at:
 rt2500usb_register_read wireless/ralink/rt2x00/rt2500usb.c:51 [inline]
 rt2500usb_init_eeprom wireless/ralink/rt2x00/rt2500usb.c:1440 [inline]
 rt2500usb_probe_hw+0x774/0x22a0 wireless/ralink/rt2x00/rt2500usb.c:1757
 rt2x00lib_probe_dev+0xba9/0x3260 wireless/ralink/rt2x00/rt2x00dev.c:1427

Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
---
 drivers/net/wireless/ralink/rt2x00/rt2500usb.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Greg Kroah-Hartman Jan. 21, 2021, 9:49 a.m. UTC | #1 
On Thu, Jan 21, 2021 at 05:20:26PM +0800, Dongliang Mu wrote:
> In the function rt2500usb_register_read(_lock), reg is uninitialized
> in some situation. Then KMSAN reports uninit-value at its first memory
> access. To fix this issue, add one reg initialization in the function
> rt2500usb_register_read and rt2500usb_register_read_lock
> 
> BUG: KMSAN: uninit-value in rt2500usb_init_eeprom rt2500usb.c:1443 [inline]
> BUG: KMSAN: uninit-value in rt2500usb_probe_hw+0xb5e/0x22a0 rt2500usb.c:1757
> CPU: 0 PID: 3369 Comm: kworker/0:2 Not tainted 5.3.0-rc7+ #0
> Hardware name: Google Compute Engine
> Workqueue: usb_hub_wq hub_event
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x191/0x1f0 lib/dump_stack.c:113
>  kmsan_report+0x162/0x2d0 mm/kmsan/kmsan_report.c:109
>  __msan_warning+0x75/0xe0 mm/kmsan/kmsan_instr.c:294
>  rt2500usb_init_eeprom wireless/ralink/rt2x00/rt2500usb.c:1443 [inline]
>  rt2500usb_probe_hw+0xb5e/0x22a0 wireless/ralink/rt2x00/rt2500usb.c:1757
>  rt2x00lib_probe_dev+0xba9/0x3260 wireless/ralink/rt2x00/rt2x00dev.c:1427
>  rt2x00usb_probe+0x7ae/0xf60 wireless/ralink/rt2x00/rt2x00usb.c:842
>  rt2500usb_probe+0x50/0x60 wireless/ralink/rt2x00/rt2500usb.c:1966
>  ......
> 
> Local variable description: ----reg.i.i@rt2500usb_probe_hw
> Variable was created at:
>  rt2500usb_register_read wireless/ralink/rt2x00/rt2500usb.c:51 [inline]
>  rt2500usb_init_eeprom wireless/ralink/rt2x00/rt2500usb.c:1440 [inline]
>  rt2500usb_probe_hw+0x774/0x22a0 wireless/ralink/rt2x00/rt2500usb.c:1757
>  rt2x00lib_probe_dev+0xba9/0x3260 wireless/ralink/rt2x00/rt2x00dev.c:1427
> 
> Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
> ---
>  drivers/net/wireless/ralink/rt2x00/rt2500usb.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/wireless/ralink/rt2x00/rt2500usb.c b/drivers/net/wireless/ralink/rt2x00/rt2500usb.c
> index fce05fc88aaf..f6c93a25b18c 100644
> --- a/drivers/net/wireless/ralink/rt2x00/rt2500usb.c
> +++ b/drivers/net/wireless/ralink/rt2x00/rt2500usb.c
> @@ -48,6 +48,7 @@ static u16 rt2500usb_register_read(struct rt2x00_dev *rt2x00dev,
>  				   const unsigned int offset)
>  {
>  	__le16 reg;
> +	memset(&reg, 0, sizeof(reg));

As was pointed out, just set reg = 0 on the line above please.

>  	rt2x00usb_vendor_request_buff(rt2x00dev, USB_MULTI_READ,
>  				      USB_VENDOR_REQUEST_IN, offset,
>  				      &reg, sizeof(reg));

Are you sure this is valid to call this function with a variable on the
stack like this?  How did you test this change?

thanks,

greg k-h
Greg Kroah-Hartman Jan. 21, 2021, 11:20 a.m. UTC | #2 
On Thu, Jan 21, 2021 at 06:59:08PM +0800, 慕冬亮 wrote:
> On Thu, Jan 21, 2021 at 5:49 PM Greg KH <gregkh@linuxfoundation.org> wrote:
> >
> > On Thu, Jan 21, 2021 at 05:20:26PM +0800, Dongliang Mu wrote:
> > > In the function rt2500usb_register_read(_lock), reg is uninitialized
> > > in some situation. Then KMSAN reports uninit-value at its first memory
> > > access. To fix this issue, add one reg initialization in the function
> > > rt2500usb_register_read and rt2500usb_register_read_lock
> > >
> > > BUG: KMSAN: uninit-value in rt2500usb_init_eeprom rt2500usb.c:1443 [inline]
> > > BUG: KMSAN: uninit-value in rt2500usb_probe_hw+0xb5e/0x22a0 rt2500usb.c:1757
> > > CPU: 0 PID: 3369 Comm: kworker/0:2 Not tainted 5.3.0-rc7+ #0
> > > Hardware name: Google Compute Engine
> > > Workqueue: usb_hub_wq hub_event
> > > Call Trace:
> > >  __dump_stack lib/dump_stack.c:77 [inline]
> > >  dump_stack+0x191/0x1f0 lib/dump_stack.c:113
> > >  kmsan_report+0x162/0x2d0 mm/kmsan/kmsan_report.c:109
> > >  __msan_warning+0x75/0xe0 mm/kmsan/kmsan_instr.c:294
> > >  rt2500usb_init_eeprom wireless/ralink/rt2x00/rt2500usb.c:1443 [inline]
> > >  rt2500usb_probe_hw+0xb5e/0x22a0 wireless/ralink/rt2x00/rt2500usb.c:1757
> > >  rt2x00lib_probe_dev+0xba9/0x3260 wireless/ralink/rt2x00/rt2x00dev.c:1427
> > >  rt2x00usb_probe+0x7ae/0xf60 wireless/ralink/rt2x00/rt2x00usb.c:842
> > >  rt2500usb_probe+0x50/0x60 wireless/ralink/rt2x00/rt2500usb.c:1966
> > >  ......
> > >
> > > Local variable description: ----reg.i.i@rt2500usb_probe_hw
> > > Variable was created at:
> > >  rt2500usb_register_read wireless/ralink/rt2x00/rt2500usb.c:51 [inline]
> > >  rt2500usb_init_eeprom wireless/ralink/rt2x00/rt2500usb.c:1440 [inline]
> > >  rt2500usb_probe_hw+0x774/0x22a0 wireless/ralink/rt2x00/rt2500usb.c:1757
> > >  rt2x00lib_probe_dev+0xba9/0x3260 wireless/ralink/rt2x00/rt2x00dev.c:1427
> > >
> > > Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
> > > ---
> > >  drivers/net/wireless/ralink/rt2x00/rt2500usb.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> > >
> > > diff --git a/drivers/net/wireless/ralink/rt2x00/rt2500usb.c b/drivers/net/wireless/ralink/rt2x00/rt2500usb.c
> > > index fce05fc88aaf..f6c93a25b18c 100644
> > > --- a/drivers/net/wireless/ralink/rt2x00/rt2500usb.c
> > > +++ b/drivers/net/wireless/ralink/rt2x00/rt2500usb.c
> > > @@ -48,6 +48,7 @@ static u16 rt2500usb_register_read(struct rt2x00_dev *rt2x00dev,
> > >                                  const unsigned int offset)
> > >  {
> > >       __le16 reg;
> > > +     memset(&reg, 0, sizeof(reg));
> >
> > As was pointed out, just set reg = 0 on the line above please.
> 
> I've sent another patch.
> 
> BTW, I set "--subject-prefix="PATCH v2" in my git-send-mail command.
> But it does not show "v2" in the subject of the new email.

You can set the "v2" in the 'git format-patch' option, right?

thanks,

greg k-h
Dongliang Mu Jan. 21, 2021, 11:25 a.m. UTC | #3 
On Thu, Jan 21, 2021 at 7:21 PM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> On Thu, Jan 21, 2021 at 06:59:08PM +0800, 慕冬亮 wrote:
> > > >       rt2x00usb_vendor_request_buff(rt2x00dev, USB_MULTI_READ,
> > > >                                     USB_VENDOR_REQUEST_IN, offset,
> > > >                                     &reg, sizeof(reg));
> > >
> > > Are you sure this is valid to call this function with a variable on the
> > > stack like this?  How did you test this change?
> >
> > First, I did not do any changes to this call. Second, the programming
> > style to pass the pointer of stack variable as arguments is not really
> > good. Third, I check this same code file, there are many code snippets
> > with such programming style. :(
>
> I know you did not change it, what I am asking is how did you test this
> change works?  I think the kernel will warn you in huge ways that using
> this pointer on the stack is incorrect, which implies you did not test
> this change :(
>

I tested this patch only with PoC. The patched kernel version did not
crash when executing the PoC.

BTW, I did not take notice of the warning information as there are
many many warnings in building KMSAN.

> thanks,
>
> greg k-h
diff mbox series

Patch

diff --git a/drivers/net/wireless/ralink/rt2x00/rt2500usb.c b/drivers/net/wireless/ralink/rt2x00/rt2500usb.c
index fce05fc88aaf..f6c93a25b18c 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2500usb.c
+++ b/drivers/net/wireless/ralink/rt2x00/rt2500usb.c
@@ -48,6 +48,7 @@  static u16 rt2500usb_register_read(struct rt2x00_dev *rt2x00dev,
 				   const unsigned int offset)
 {
 	__le16 reg;
+	memset(&reg, 0, sizeof(reg));
 	rt2x00usb_vendor_request_buff(rt2x00dev, USB_MULTI_READ,
 				      USB_VENDOR_REQUEST_IN, offset,
 				      &reg, sizeof(reg));
@@ -58,6 +59,7 @@  static u16 rt2500usb_register_read_lock(struct rt2x00_dev *rt2x00dev,
 					const unsigned int offset)
 {
 	__le16 reg;
+	memset(&reg, 0, sizeof(reg));
 	rt2x00usb_vendor_req_buff_lock(rt2x00dev, USB_MULTI_READ,
 				       USB_VENDOR_REQUEST_IN, offset,
 				       &reg, sizeof(reg), REGISTER_TIMEOUT);