Re: [PATCH 1/1] r8152: fix NULL pointer dereference in r8152_poll

[Petr Vorel]

> > > Unfortunately this doesn't work. Code in r8152.c doesn't use
> > > local_bh_enable()/local_bh_disable(). I tried to lock it with
> > > spin_lock_bh()/spin_unlock_bh() and with mutex_lock()/mutex_unlock()
> > > but neither work.

> > The local_bh_disable() / local_bh_enable() definitely is the right
> > answer to the issue you described.

> > It does not matter what code in r8152.c currently does.

> > https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/commit/?id=8cf699ec849f4ca1413cea01289bd7d37dbcc626


> You also have to protect other napi_schedule(), like the ones in
> rtl_work_func_t() or rtl8152_post_reset()

I've tested that before :-). I'll be more precise what "not working" means: it 
fixes
invalid pointer issue, but kernel crashes for different reason:

 ...
Call Trace:
 
 net_rx_action+0x23c/0x3f0
 __do_softirq+0x104/0x2e1
 ? usb_runtime_suspend+0x70/0x70 [usbcore]
 do_softirq_own_stack+8x1c/0x30
 
 do_softirq.part.18+0x41/0x50
 __local_bh_enable_ip+0x88/0xa0
 rtl8152_resume+0xe2/0x1a0 [r8152]
 usb_resume_interface.isra.60x99/0xf0 [usbcore]
 usb_resume_both+0x6a/0x130 [usbcore]
 __rpm_callback+0xb9/0x1f0
 rpm_callback+Ox5f/0x80
 ? usb_runtime_suspend+0x70/0x70 [usbcore]
 usb_resume+0x495/0x6b0
 ? update_load_avg+Ox79/0x520
 ? update_load_avg+Ox79/0x520
 ? refcount_dec_and_test+0x11/0x20
 __pm_runtime_resume+0x3f/0x60
 usb_autoresume_device+0x23/0x50 [usbcore]
 usb_dev_open+0xe7/0x250 [usbcore]
 chrdev_open+0xa1/0x200
 do_dentry_open+0x20a/0x2f0
 ? cdev_put+0x30/0x30
 vfs_open+0x4c/0x70
 ? may_open+0x9b/0x100
 path_openat+0x5ec/0x1430
 do_filp_open+0x7e/0xe0
 ? __vfs_write+0x28/0x140
 ? __alloc_fd+0xb2/0x160
 do_sys_open+0x123/0x200
 SyS_open+0x1e/0x20
 entry_SYSCALL_64_fastpath+0x1e/0xad
 ...
 Kernel panic - not syncing: Fatal exception in interrupt
 ...

Patch: http://pastebin.com/Uejjc0Bh (I don't post patch here, as it's not 
working).


Kind regards,
Petr

Re: [PATCH 1/1] r8152: fix NULL pointer dereference in r8152_poll

[Eric Dumazet]

On Mon, 2017-03-13 at 08:44 -0700, Eric Dumazet wrote:
> On Mon, 2017-03-13 at 16:37 +0100, Petr Vorel wrote:
> > Hi Eric,
> > 
> > > > The proper work around is to enclose the napi_schedule() in a
> > > > local_bh_enable()/local_bh_disable()  pair.
> > 
> > > Something like :
> > > --- a/drivers/net/usb/r8152.c
> > > +++ b/drivers/net/usb/r8152.c
> > > @@ -3703,8 +3703,10 @@ static int rtl8152_resume(struct usb_interface 
> > > *intf)
> > >   napi_enable(>napi);
> > >   clear_bit(SELECTIVE_SUSPEND, >flags);
> > >   smp_mb__after_atomic();
> > > + local_bh_disable();
> > >   if (!list_empty(>rx_done))
> > >   napi_schedule(>napi);
> > > + local_bh_enable();
> > 
> > Unfortunately this doesn't work. Code in r8152.c doesn't use
> > local_bh_enable()/local_bh_disable(). I tried to lock it with
> > spin_lock_bh()/spin_unlock_bh() and with mutex_lock()/mutex_unlock()
> > but neither work.
> 
> The local_bh_disable() / local_bh_enable() definitely is the right
> answer to the issue you described.
> 
> It does not matter what code in r8152.c currently does.
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/commit/?id=8cf699ec849f4ca1413cea01289bd7d37dbcc626


You also have to protect other napi_schedule(), like the ones in
rtl_work_func_t() or rtl8152_post_reset()

Re: [PATCH 1/1] r8152: fix NULL pointer dereference in r8152_poll

[Eric Dumazet]

On Mon, 2017-03-13 at 16:37 +0100, Petr Vorel wrote:
> Hi Eric,
> 
> > > The proper work around is to enclose the napi_schedule() in a
> > > local_bh_enable()/local_bh_disable()  pair.
> 
> > Something like :
> > --- a/drivers/net/usb/r8152.c
> > +++ b/drivers/net/usb/r8152.c
> > @@ -3703,8 +3703,10 @@ static int rtl8152_resume(struct usb_interface *intf)
> > napi_enable(>napi);
> > clear_bit(SELECTIVE_SUSPEND, >flags);
> > smp_mb__after_atomic();
> > +   local_bh_disable();
> > if (!list_empty(>rx_done))
> > napi_schedule(>napi);
> > +   local_bh_enable();
> 
> Unfortunately this doesn't work. Code in r8152.c doesn't use
> local_bh_enable()/local_bh_disable(). I tried to lock it with
> spin_lock_bh()/spin_unlock_bh() and with mutex_lock()/mutex_unlock()
> but neither work.

The local_bh_disable() / local_bh_enable() definitely is the right
answer to the issue you described.

It does not matter what code in r8152.c currently does.

https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/commit/?id=8cf699ec849f4ca1413cea01289bd7d37dbcc626

Re: [PATCH 1/1] r8152: fix NULL pointer dereference in r8152_poll

[Petr Vorel]

Hi Eric,

> > The proper work around is to enclose the napi_schedule() in a
> > local_bh_enable()/local_bh_disable()  pair.

> Something like :
> --- a/drivers/net/usb/r8152.c
> +++ b/drivers/net/usb/r8152.c
> @@ -3703,8 +3703,10 @@ static int rtl8152_resume(struct usb_interface *intf)
>   napi_enable(>napi);
>   clear_bit(SELECTIVE_SUSPEND, >flags);
>   smp_mb__after_atomic();
> + local_bh_disable();
>   if (!list_empty(>rx_done))
>   napi_schedule(>napi);
> + local_bh_enable();

Unfortunately this doesn't work. Code in r8152.c doesn't use 
local_bh_enable()/local_bh_disable(). I tried to lock it with 
spin_lock_bh()/spin_unlock_bh() and with mutex_lock()/mutex_unlock() but 
neither work.


Kind regards,
Petr

Re: [PATCH 1/1] r8152: fix NULL pointer dereference in r8152_poll

[Eric Dumazet]

On Mon, 2017-03-13 at 06:18 -0700, Eric Dumazet wrote:
> On Mon, 2017-03-13 at 13:47 +0100, Petr Vorel wrote:
> > commit 7489bdadb7d1 (r8152: check rx after napi is enabled) causes null
> > pointer dereference when using device as under root:
> > 
> >  # rmmod r8152 # or lsusb -v
> > NOHZ: local_softirq_pending 08
> > BUG: unable to handle kernel NULL pointer dereference at 0008
> > IP: r8152_poll+0x125/0x570 [r8152]
> > PGD 89b4cf067
> > PUD 898ff2067
> > PMD 0
> > Oops: 0002 [#1] PREEMPT SMP
> > 
> > Signed-off-by: Petr Vorel 
> > ---
> > NOTE: This is just a workaround, I suppose, there is better way how to fix 
> > that
> > (which allows keeping scheduling the napi for rx after napi_enable()).
> > ---
> >  drivers/net/usb/r8152.c | 2 --
> >  1 file changed, 2 deletions(-)
> > 
> > diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
> > index 986243c932cc..79c665a89a47 100644
> > --- a/drivers/net/usb/r8152.c
> > +++ b/drivers/net/usb/r8152.c
> > @@ -3703,8 +3703,6 @@ static int rtl8152_resume(struct usb_interface *intf)
> > napi_enable(>napi);
> > clear_bit(SELECTIVE_SUSPEND, >flags);
> > smp_mb__after_atomic();
> > -   if (!list_empty(>rx_done))
> > -   napi_schedule(>napi);
> > } else {
> > tp->rtl_ops.up(tp);
> > netif_carrier_off(tp->netdev);
> 
> 
> The proper work around is to enclose the napi_schedule() in a
> local_bh_enable()/local_bh_disable()  pair.

Something like :

diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
index 
986243c932ccd6fe19c592805c1c63274f5e..b6bb1720c383946ea6142ec2f79f5b7a69031d7f
 100644
--- a/drivers/net/usb/r8152.c
+++ b/drivers/net/usb/r8152.c
@@ -3703,8 +3703,10 @@ static int rtl8152_resume(struct usb_interface *intf)
napi_enable(>napi);
clear_bit(SELECTIVE_SUSPEND, >flags);
smp_mb__after_atomic();
+   local_bh_disable();
if (!list_empty(>rx_done))
napi_schedule(>napi);
+   local_bh_enable();
} else {
tp->rtl_ops.up(tp);
netif_carrier_off(tp->netdev);

Re: [PATCH 1/1] r8152: fix NULL pointer dereference in r8152_poll

[Eric Dumazet]

On Mon, 2017-03-13 at 13:47 +0100, Petr Vorel wrote:
> commit 7489bdadb7d1 (r8152: check rx after napi is enabled) causes null
> pointer dereference when using device as under root:
> 
>  # rmmod r8152 # or lsusb -v
> NOHZ: local_softirq_pending 08
> BUG: unable to handle kernel NULL pointer dereference at 0008
> IP: r8152_poll+0x125/0x570 [r8152]
> PGD 89b4cf067
> PUD 898ff2067
> PMD 0
> Oops: 0002 [#1] PREEMPT SMP
> 
> Signed-off-by: Petr Vorel 
> ---
> NOTE: This is just a workaround, I suppose, there is better way how to fix 
> that
> (which allows keeping scheduling the napi for rx after napi_enable()).
> ---
>  drivers/net/usb/r8152.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
> index 986243c932cc..79c665a89a47 100644
> --- a/drivers/net/usb/r8152.c
> +++ b/drivers/net/usb/r8152.c
> @@ -3703,8 +3703,6 @@ static int rtl8152_resume(struct usb_interface *intf)
>   napi_enable(>napi);
>   clear_bit(SELECTIVE_SUSPEND, >flags);
>   smp_mb__after_atomic();
> - if (!list_empty(>rx_done))
> - napi_schedule(>napi);
>   } else {
>   tp->rtl_ops.up(tp);
>   netif_carrier_off(tp->netdev);


The proper work around is to enclose the napi_schedule() in a
local_bh_enable()/local_bh_disable()  pair.

[PATCH 1/1] r8152: fix NULL pointer dereference in r8152_poll

[Petr Vorel]

commit 7489bdadb7d1 (r8152: check rx after napi is enabled) causes null
pointer dereference when using device as under root:

 # rmmod r8152 # or lsusb -v
NOHZ: local_softirq_pending 08
BUG: unable to handle kernel NULL pointer dereference at 0008
IP: r8152_poll+0x125/0x570 [r8152]
PGD 89b4cf067
PUD 898ff2067
PMD 0
Oops: 0002 [#1] PREEMPT SMP

Signed-off-by: Petr Vorel 
---
NOTE: This is just a workaround, I suppose, there is better way how to fix that
(which allows keeping scheduling the napi for rx after napi_enable()).
---
 drivers/net/usb/r8152.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
index 986243c932cc..79c665a89a47 100644
--- a/drivers/net/usb/r8152.c
+++ b/drivers/net/usb/r8152.c
@@ -3703,8 +3703,6 @@ static int rtl8152_resume(struct usb_interface *intf)
napi_enable(>napi);
clear_bit(SELECTIVE_SUSPEND, >flags);
smp_mb__after_atomic();
-   if (!list_empty(>rx_done))
-   napi_schedule(>napi);
} else {
tp->rtl_ops.up(tp);
netif_carrier_off(tp->netdev);
-- 
2.12.0